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MIf 

IE VENTILA1 

non 


MADE EASY, 



WITH AN APPENDIX CONTAINING DETAILED 


ANSWERS to 155 QUESTIONS, 


SELECTED FROM VARIOUS 

AMERICAN EXAMINATIONS 

FOR 

MINE INSPECTORS and MINE FOREMEN. 


BY 

William Fairley, Ph.D.. F. G. S., M. E., etc. 


SCRANTON, PA. 
THE COLLIERY ENGINEER 



1894. 



























Entered according to the Act of Congress, in the year 1894, by 
THE COLLIERY ENGINEER CO., 

In the Office of the Librarian of Congress at Washington. 




PREFACE. 


Iii preparing this little work on Mine Ventilation, the author’s 
object was the production of a thorough but concise work for the 
use of American mine officials and mining students. It is there¬ 
fore written in as simple language as possible, and the principles 
of ventilation are carefully adapted to meet the conditions 
existing in American mines. The work was originally written 
for publication in The Colliery Engineer during the author’s 
engagement as assistant editor of that journal, and while lie 
was residing in the United States, and had every opportunity 
to learn the wants of American miners. 

When the work was completed, at the suggestion of the 
editors of The Colliery Engineer, questions asked at all the 
State examinations of candidates for mine inspectorships and 
for certificates of competency as mine foremen, were collected. 
From these, one hundred and fifty-five were selected and answers 
to them prepared. These questions and answers form an ap¬ 
pendix to this volume. They will be found very useful to 
students preparing themselves for examinations. 
































INDEX. 


Chapter I. 

Facts, Rules, Scientific Memoranda and Max¬ 
ims, Relating to Air, Gases, Colliery Explo¬ 
sions, and the Ventilation of Mines. 

PAGE 

1. Pure Atmospheric Air..^. 11 

2. Mean Temperature of Air_ 11 

3. Weight of Aiiv.._.... 11 

4. Pressure of the Atmosphere_ 11 

5. Weight of Air at different Elevations_ 12 

0. Height of Columns of Air, Water and Mercury 

to balance each other_ 12 

7. Height above Sea Level at which Man can exist 12 

8. Comparative weights of Air and Water. 12 

9. Barometer and Atmospheric Pressure. .. 12 

10. Increase of Atmospheric Pressure, with Depth. 12 

11. Decrease of Atmospheric Pressure and Tem¬ 

perature on ascending_ 12 

12. Increase of Temperature below surface of the 

earth_ 12 

14. Definition of Mine Ventilation_ 13 

15. Laws of Pennsylvania in regard to Ventilation 13 

16. Principle of Mine Ventilation. 13 

17. Natural Ventilation .. 13 

18. Method by which Furnaces and Fans produce 

Ventilation _ .. 13 

19. Furnace Ventilation_ 14 

20-21. Dangers of, and Objections to Furnace Ventila¬ 
tion . 14 

22. Cost of Furnace Ventilation_ 15 

23. Dumb-drift_ 15 





















VI 


INDEX. 


24. 

25. 

26. 
27. 

28-29. 

30-31-32. 

33. 

34. 

35. 

36. 
37-38. 
39-40. 

41. 

42. 
43-44. 

45-45^. 

46. 

47-48. 

49-50. 

51-54. 

55. 

56. 

57. 

58. 
59-60. 

61. 

62. 

63. 

64. 

65. 


Ventilating Fans ._... _ 

Tabulated Results of Experiments with the 

Capell Fan______ 

Tabulated Results of Experiments with the 

Guibal Fan_ .__ 

Tabulated Results of Experiments with the 

Waddle Fan__ 

The Relations between Power, Pressure and 

Quantity_ ___ 

Relative Power for different sized Airways 

(Tabulated)... 

Effect of Splitting the air, and Pennsylvania 

Laws upon same.... 

Regulation of quantities in different Splits_ 

To Ascertain Air pressure (Table)_ 

Proper Velocity of Air._..... 

Ventilating single places and tunnels__ 

Expansion of Gases in Goaves on change of 

Atmospheric pressure__ 

Weights of Mercury, Water, Air and Fire- 

Damp Compared___ 

Blowers___ 

Volcanic disturbances and the issue of Gas_ 

Blasting, and the Laws of Pennsylvania regard¬ 
ing the same____ 

Ascensional Ventilation_ 

Ventilation of Shallow and Deep Pits_ 

Effects of Wind and Weather on Ventilation. _ 

Remarks on Ventilation_ _ 

Diffusion of Gas___ 

Walling back Gas... 

Proper place for Stoppings... .... 

Safety Lamps_ 

Rules for Gaseous Mines___ 

Mixed Lights____ 

How to act in case of Explosion_ 

Removal of Fire-Damp. ___ 

Relative number of Accidents on different Days 

of the week___ 

Ventilation Plans____ 


VAGET 

15- 

16 


16 

17 

18 


18 


19 

19 

20 
20 
20 


21 


22 

22 

23 


23 

23 


24 

24 

24 


24 

25 
25 
25 
25 
25 


25 

26 

26 


26 





























INDEX. 


66 . 

67. 

68 . 

69. 

70. 

71. 

72. 

73. 

74. 


76. 

77-78. 


vii 


PACE 

Percentages of Accidents from different causes 26 

Explosive Gaseous Mixtures_ 27 

Suffocation by Fire-Damp..... 27 

Carbonic Acid Gas_ ___ 27 


Carbonic Oxide.. 27 

Carbureted Hydrogen_ 28 

Olefiant Gas_ 28 

Sulphureted Hydrogen._ 28 

Sulphurous Acid Gas_ 28 

After-Damp____ .... 28 

Gob-Fires__ 29 

Natural Gas_ 29 


Chapter II. 

Explanation of Terms Used in the Subject of 
Mine Ventilation_...31 to 47 


Chapter III. 

Practical Notes on Coal Dust and Colliery Ex¬ 
plosions _... _.....48 to 5$ 


Chapter IV. 

Rules and Formulee Applicable to Various Ques¬ 
tions Relating to the Ventilation of Mines, 
the Pressure and Temperature of the Atmos¬ 
phere, and to the Circulation of Air in Pass¬ 
ages, etc. 

The Co-efficient of Friction____ 52 

I. Rules applying to Air Moving in Underground 

Passages..... 53 

II. To ascertain the Motive Column... 54 

III. Diameter of Round Air-way to pass same Quantity 

as Square One____ 54 

IV. Relative Pressure to pass equal Quantities, with 

different Areas or Perimeters....... 55 

V. Relative Quantities that will pass Air-ways sub¬ 
ject to same Pressure but of different dimen¬ 
sions .. ....... 55 





















viii 


INDEX. 


PAGfi 

To reduce a continuous undivided Road of Vari¬ 
ous dimensions, to one typical Road of Uniform 

size throughout___ _... 55 

To convert French to English Co-efficient of fric¬ 
tion _____ 55 

To find Quantity of Air with a given Horse power 

and efficiency of engine____ 55 

To find the Weight of a cubic foot of Air at any 

Temperature or Height of Barometer_ 55 

To convert Thermometer Scales of Fahrenheit, 

Centigrade and Reaumur into each other_ 56 

To measure Air in a Mine by Gunpowder. __ 56 

Formulae relating to Equivalent Orifice.. __ 56 

Formulae relating to Theoretical Depression, or 

pressure of Air due to Final Velocity___ 56 

Relation between Quantities of Air Produced by 
two fans working Separately and Together_ 57 

Chapter V. 

Useful Tables Relating to Mine Ventilation, Air 
and Gases. 

I. Table of the Co-efficient of friction in the flow of 
Air through Passages with different kinds of 
surface according to different Authorities, ex¬ 
pressed in terms agreeable to the Measures used 
in the United States, Great Britain, France and 


German} 7 ______ 58 

II. Table showing the pressure per square foot in 
pounds due to the Flow of Air at different Ve¬ 
locities in Roads of different dimensions... 59 

III. Table showing the Quantity of Air that will flow 

through a passage one foot area, at different ve¬ 
locities, and the pressure due to a length of one 
mile. 59 

IV. Table showing length of roads of different dimen¬ 

sions offering resistance equal to one inch of 

water gauge. 60 

V. Table showing the water-gauge due to 30,000 
cubic feet of Air passing through Mines with 
different equivalent orifices. 61 


VI. 

VII. 

VIII. 

IX. 

X. 

XI. 

XII. 

XIII. 

XIV. 














Index. 


ix 

PAGE 

VI. Table of the values of the theoretical depression 
expressed in inches of water-gauge and head of 

Air in feet... G1 

VII. Table of Elementary and Compound Gases, with 

their properties____ 62 

VIII. Table of the weight of a cubic foot of Air, in 

Decimals of a Pound, at different Temperatures 63 

IX. Table showing comparative composition of Lig¬ 

nite, Bituminous Coal, Anthracite Coal, Wood 
and Peat_ 64 

X. Table showing Square Root of Water-gauge read¬ 

ings and Pressures. ____ 65 

XI. Table of the Volume, Density, and Pressure of 

Air at Various Temperatures___ 66 

XII. Table showing the relative Variations in Mercury, 
Water and Gas by changes of Atmospheric 
Pressure. 67 

XIII. Table showing the Pressure of the Atmosphere 

per square inch and per square foot at various 
readings of the Barometer__ 67 

XIV. Table to Illustrate the Chemical Change which 

takes place in Breathing__ 68 

XV. Table of Analyses of Different Compound Gases. 68 

XVI. Table of Analyses of Coal Gas from Cannel Coal 69 

XVII. Table of Analyses of Coal Gas from Bituminous 

Coal. 70 

XVIII. Table of the Expansion of Air by Heat__ 70 

XIX. Table showing the pressure of Air in Shafts, per 
square foot of Area at Various Depths and Tem¬ 
peratures . 71 

XX. Table showing Barometric readings correspond¬ 
ing with different Altitudes, in French and En¬ 
glish Measures.. 72 

XXI. Table of Comparative Readings of Thermometer 
on the different Scales—Centigrade, Reaumur 

and Fahrenheit.. 72 

XXII. Table of Velocities and Pressures of Air.. 73 

XXIII. Table showing the Quantity of gas in cubic feet 

obtained from Coal-- 74 

















INDEX. 


X 


page 

XXIV. Table showing the Conversion of Column of 

Water to Column of Mercury and Fire-Damp.. 74 
XXV. Table showing the relative weight of Water and 
Air at different Temperatures, with deductions 
made therefrom____ 75 


Chapter VI. 


Legislation on the Subject of Mine Ventilation 
in the United States and Foreign Countries. 


Prussia..... 

England_*. . „. 

Nova Scotia...__ 

Victoria_ _ 

Anthracite Law of Pennsylvania 
Bituminous Law of Pennsylvania 

Ohio..... 

Iowa___ 

Washington__ 

Tennessee.. 

West Virginia.. 

Kentucky........ 

Alabama...... 

Kansas.... 

Arkansas__ 

Indiana.. 

Territories.... 


7(1 

77 

77 

78 
78 
78 

78 

79 
79 
79 
79 
79 
79 

79 

80 
80 
80 


Appendix. 

Questions and Answers on subjects relating to 
Mine Ventilation, Atmospheric Air and Gases, 
mainly selected from various American Ex¬ 
aminations for Mine Inspectors and Mine 
Foremen.. ....81 to 110 





















MINE VENTILATION MADE EAST 


CHAPTER I. 

FACTS, RULES, SCIENTIFIC MEMORANDA AND MAXIMS RELATING 
TO AIR, GASES, COLLIERY EXPLOSIONS, AND THE VENTILA¬ 
TION OF MINES. 

1. Pure atmospheric air consists of a mechanical mixture of 
seventy-seven parts, by weight, of nitrogen and twenty-three of 
oxygen, with small portions of carbonic acid and ammonia, 
and a varying proportion of watery vapor. 

Many impurities have been found in the air of towns by 
examining the rains which have fallen. The air at the sea- 
coast, and at great heights, is the freest from impurities, and 
the porportion of ammonia is found to decrease in ascending. 
The organic matter contained in the air depends very much 
upon the density of the population. The return air of mines 
is often very much vitiated in its passage through the excava¬ 
tions. 

2. The mean temperature of the air in Philadelphia is 68‘6 
degrees Fahrenheit in summer, and 38*3 degrees Fahrenheit in 
winter. The temperature of air in the interior of mines, 
especially deep mines, is pretty nearly constant all the year 
round; this fact, coupled with that of the variation of tempera¬ 
ture at the surface, accounts for the uncertainty of natural 
ventilation. 

3. The weight of air is about 31 grains per 100 cubic inches 
at ordinary pressure and temperature, but it varies according 
to the reading of the barometer. It becomes less and less in 
weight as we ascend ; the weight of a cubic foot at sea-level 
under ordinary conditions is -076097 pound. It becomes lighter 
as the temperature increases; thus, 1000 cubic feet at 32 
degrees Fahrenheit weigh 81 lbs.; at 110 degrees 1000 feet weigh 
70 lbs.; and at 200 degrees, 60 lbs. 

4. The average pressure of the atmosphere at the level of the 
sea, is equal to 14-7 lbs. per square inch, or 2116*8 lbs. per 
square foot. The total pressure on the convex surface pf the 



12 


earth was calculated by the late Dr. Olinthus Gregory to 
amount to 10,686,000,000 hundreds of millions of pounds. This 
may be expressed as ten trillions, six hundred and eighty-six 
thousand billions. Sir John Herschel’s calculation of this was 
11 % trillions of pounds, which is about ten per cent, more than 
that of Dr. Gregory. 

5. It is calculated that at a height of about miles above 
the sea-level the weight of a cubic foot of air is only one-half 
what it is at the surface of the earth, at seven miles only one- 
fourth, at fourteen miles only one-sixteenth, at twenty-one 
miles only one sixty-fourth, and at a height of over forty--five 
miles it becomes so attenuated as to have no appreciable 
weight. 

6. The opinion is generally held that atmospheric air en¬ 
circles the earth for a distance of forty-five miles from the sur¬ 
face, and that a column of air that height, one of water 32 to 
34 ft. high, and one of mercury about 30 inches high, on an 
average balance each other. 

7. A man cannot breathe at a greater height than seven 
miles from the surface. On one occasion when Mr. Glaisher, 
the celebrated aeronaut, had attained a height of over four 
miles in a balloon, his hands became quite blue, and he experi¬ 
enced a qualmish sensation in the brain and stomach, resem¬ 
bling the approach of sea-sickness,—great cold and a difficulty 
of breathing were likewise felt. 

8. Air is 821 times lighter than water; the student may cal¬ 
culate this for himself from the following data—air in ordinary 
conditions weighs *076097 lb. per cubic foot, water 62*5 lbs., 
then dividing one into the other he will get 821. 

9. A fall in the barometer of one inch represents a reduction 
in the pressure of the atmosphere of half a pound per square 
inch or 72 lbs. per square foot, so that an underground excava¬ 
tion six feet square, with an increase of an inch in the barom¬ 
eter, has an increased pressure on the face, of 2592 pounds. 

10. The pressure of the atmosphere increases with the depth 
of shafts, equal to about one inch rise in the barometer for each 
150 fathoms (900 ft.) increase in depth : this may be taken by 
practical miners as a rough and ready rule for ascertaining the 
depth of shafts. 

11. Both the barometer and thermometer show a lower read¬ 
ing in ascending from the surface; for example, at a height of 
20,000 feet, the temperature is 40 degrees less than at the sur¬ 
face, and the reading of the barometer is only about one-half of 
the reading at the surface, but the variation both in tempera¬ 
ture and pressure is not regular. In the month of August, on 
one occasion, Mr. Glaisher found the temperature to be 24 
degrees at a height of 23,000 feet. 

12. It is generally reckoned that the temperature of the rocks 
composing the earth gradually increases in descending from the 
surface, at the rate of one degree on the Fahrenheit scale for 


13 


every 60 feet increase in depth, but different results have been 
obtained by various observers on the question. 

14. Mine ventilation is understood to mean the provision for 
a constant supply of fresh air, and its regular flow throughout 
the underground workings, in a sufficiently copious quantity to 
destroy the vitiating effects of the carbonic acid, and water, 
added to it by the breathing of animals and burning of lights, 
by the gases issuing from the rocks, or by any other noxious 
emanations, all of which should be carried away as fast as they 
are engendered. 

15. Although 666 cubic feet of air have been reckoned suffi¬ 
cient to sustain a man for twenty-four hours, much more than 
that should be reckoned upon. By section 7, Article X., of the 
Anthracite Mine Law of Pennsylvania, 1891, it is provided 
that: “ All air passages shall be of a sufficient area to allow the 
free passage of not less than two hundred (200) cubic feet of air 
per minute for every person working therein.” 

Section 1, of Article IV., of An Act Relating- to the Bitumi¬ 
nous Coal Mines of Pennsylvania, approved May 15th, 1893, pro¬ 
vides that: “ The operator or superintendent of every bitumi¬ 
nous coal mine, whether shaft, slope or drift, shall provide and 
hereafter maintain ample means of ventilation for the circula¬ 
tion of air through the main-entries, cross-entries and all other 
working places to an extent that will dilute, carry off and 
render harmless the noxious or dangerous gases generated in 
the mine, affording not less than one hundred (100) cubic feet 
per minute for each and every person employed therein, but in 
a mine where fire-damp has been detected the minimum shall 
be one hundred and fifty (100) cubic feet per minute for each 
person employed therein, and as much more in either case as 
one or more of the mine inspectors may deem requisite.” 

16. In order to create and maintain a circulation of air 
through a mine, it is necessary to have at least one inlet and 
one outlet, and sufficient passages between them for the flow of 
air, all of sufficient size, and either to rarefy the air-current by 
heat or to exhaust or pump it out at one end—that is the outlet 
column—or to compress the air in the inlet column to obtain 
sufficient pressure. 

17. The ventilating pressure necessary for putting air in 
motion may be obtained by either natural or artificial means. 
Natural ventilation, on account of the change of the weather, 
both as regards the direction and force of the wind, and varia¬ 
tion in barometer and thermometer, is uncertain and unreliable, 
particularly in shallow mines, and need not be further referred 
to here. The artificial means used are generally furnaces and 
fans or mechanical ventilators. 

18. Both furnaces and fans have the same effect in producing 
ventilation—that is to say, their operation results in altering 
the density of the air at one end of the column, thus destroying 
the equilibrium of pressure in the downcast and upcast shafts ; 


14 


and so long as the pressure is maintained by the means applied, 
the movement of the air will be continued in the direction to 
where it is most attenuated. 

19. The ventilating pressure obtained by a furnace depends 
mainly upon the amount of heat communicated to the air-cur¬ 
rent in the upcast, the depth of the shafts, and the area pro¬ 
vided for the escape of the heated air ; and for the current to 
be regular, it is necessary that the furnace should be kept con¬ 
stantly at about the same degree of heat. In furnace ventila¬ 
tion the temperature of the air in the downcast is seldom below 
40 degrees, and rarely averages more than 200 degrees in the 
upcast; this gives a pressure of 11*6 at a depth of 200 yards ; of 
17-4 at 300 yards ; and of 23*2 per square foot at 400 yards. (See 
Table “Showing Pressure of Air in Shafts,” in a subsequent 
chapter.) 

20. There is great risk of fire and of explosions in the use of 
furnaces, but the rapidity with which the use of mechanical 
appliances has been extended to the ventilation of coal mines 
of late years shows that eventually the furnace will fall alto¬ 
gether into disuse; as it may well do from the many dangers 
and inconveniences attending it. 

The use of furnaces is forbidden under the 1891 Anthracite 
Mine Law of Pennsylvania—the section referring to the matter 
reads as follows : 

“ It shall not be lawful to use a furnace for the purpose 
of ventilating any mine wherein explosive gases are gener¬ 
ated.” 

In the mines of Great Britain, according* to General Rule 2, if 
the mines are gaseous, furnaces are not prohibited, but the 
return air is to be carried off clear of the fire by means of a 
dumb-drift. 

21. Another objection to the furnace is, that the fumes aris¬ 
ing from it eat away the metal casing of the shafts, and injure 
the wire ropes when coal is wound through the upcast. Mr. 
Daglisli thoroughly explained this before a meeting of the 
North of England Institute of Engineers in 1859, when he said 
the injury was not owing to the direct action of the heat of the 
furnace itself, but to the chemical effect of its vapors princi¬ 
pally in action opposite the entrance of the furnace drift into 
the shaft. “The sulphur in the coals volatilized by the fur¬ 
nace, combines with a portion of oxygen to form sulphurous 
acid ; this, possessing the property of taking up another atom 
of oxygen when in contact with moist air, forms hydrated sul¬ 
phuric acid in the upcast shaft, which, diluted with the other 
shaft-water, passes down the rope, and as the boiling point of 
hydrated sulphuric acid is greatly higher than that of water, 
the solution increases in strength as it falls down the shaft, 
and becomes highly concentrated and corrosive when opposite 
the furnace drift, and subjected to a temperature of probably 
300 degrees. Water after passing down a deep and moist up- 


15 


cast shaft is sensibly acid to the taste and reddens litmus 
paper.” 

22. Furnace ventilation cannot in point of economy success¬ 
fully compete with mechanical ventilation. As to the cost per 
horse-power in the air per hour, the late Mr. Morison showed 
that with furnaces it varied from the third of a penny to three 
pence half-penny, whereas with fans the working cost was 
only half a farthing; that is roughly speaking, the working of 
furnaces costs four cents, and the working of fans one-fourth 
of a cent per horse-power. (Transactions of North of England 
Institute of Engineers, Vol. XIX.) 

23. The dumb-drift which was adopted in English coal mines 
more than fifty years ago for ensuring safety in furnace venti¬ 
lation, very much reduces the power of the furnace, because it 
decreases the length of the heated air column; and there is 
likewise the additional friction in the upcast of the air which 
feeds the furnace, but which does not circulate through the 
mine. A furnace probably heats the air up to 300° F., where¬ 
as, the temperature of the return air passing up the dumb- 
drift, in all likelihood does not amount to more than 90° ; there 
is, therefore, a loss of 
the extra heat of the 
furnace, so far up the 
shaft, as the air enters 
it from the dumb-drift; 
the length of the heated 
column of air being re¬ 
duced by the vertical dis¬ 
tance from the furnace- 
level to where the dumb- 
drift enters the upcast as 
shown Fig. 1, because 
the main body of air 
travels along the dumb- 
drift, and not over the 
furnace. Of course, it is understood in such a case that the 
furnace is only supplied by a scale of air simply sufficient to 
promote combustion. 

24. There are two classes of fans—namely : that which forces 
the air into the mine, and that which exhausts it from the mine; 
but the latter class is the one chiefly in use. There is a great 
variety of exhausting fans, each of the respective inventors of 
which claims for his own some particular merit. It is not 
intended here to recommend any special fan, but to give 
general information on the work produced by some of the 
mechanical ventilators. As to the kind of fan to be adopted at 
a colliery, there are two points to be considered, the cost of 
erection and the probable useful effect it will produce. Ac¬ 
cording to the reports of various experimenters, the useful 
effect of different fans has been ascertained to vary as much 













16 


as from 30 to 80 per cent, of the power applied. In England, 
both the Guibal and the Waddle have been favorite fans for a 
long time, but of late, quick-running ventilators, such as the 
Capell and Chandler, are being very much adopted. 

25. The high-speed Capell fan has recently become exten¬ 
sively used in English and German collieries, and the follow¬ 
ing details are given of some of the work it has done : 

TABULATED RESULTS OF EXPERIMENTS WITH CAPELL FAN. 


Colliery where Ven¬ 
tilator is at Work. 

Diameter and Width 
of Ventilator. 

Size of Engine. 

Revolutions of Fan. 

Volume of air in cubic 

feet per minute. 

Water-Gauge. 

Useful effect per cent. 

Waleswood_ 

10'0'x8'6" 

ins. 

24x36 

210 

108,700 

3*1 

82-0 

East Howie ... 

12'0"xl0'0" 

20 x 36 

200 

156,510 

3*3 

71-6 

Shirland_ 

12'6"x5'8" 

18 x24 

212 

123,200 

3-85 

7P0 

White Lea_ 

8'0"x4'0" 

12 x 25 

288 

56,814 

2*5 

78*27 

Ioachin Essen . 

8'0"x5'6" 


333 

66,500 

4-7 

73-9 


With respect to this fan it is stated that at the Prosper No. 1 
Colliery, Borbeck, Westphalia, it exhausted 126,480 cubic feet 
of air per minute with a water-gauge of 10-7 inches, this is the 
highest water-gauge the writer has known a fan to be worked 
at. The results given in this table of the work done by the 
fan at Wales wood are from experiments made by the writer. 

26. A large number of Guibal fans have been erected at the 
coal mines of America, England and on the Continent of 
Europe. Being a fan of large capacity, it does not require to 
run at so great a velocity as some of the other fans to exhaust 
the same volume of air. Makers of this fan some time back 
issued the following table to represent practically the duty of 
the various dimensions at a fair working speed. This, how¬ 
ever, varies naturally with the condition of the shafts and 
air-ways of the mines, sometimes exceeding the tabulated 
figures in cases of large air-passages, and at other times falling 
short of them where the currents are hindered by heavy fric¬ 
tional resistance. 


















17 


Diameter of Ventilator. 

Width of Ventilator. 

Volume of Air per 
minute. 

In Cubic Feet. 

Water-Gauge in Inches. 

Suitable 

-Size of En¬ 

gine. 

Diameter of 

Cylinder. 

Length of 

Stroke. 

ft. 

ft. 



ins. 

ins. 

ins. 

10 

4 

20 

000 

0-50 

6 

12 

12 

4 

30 

000 

0-65 

12 

12 

16 

534 

40 

000 

0-80 

12 

18 

20 

634 

50 

000 

1-20 

18 

18 

24 

8 

70 

000 

2-00 

20 

20 

30 

10 

100 

000 

2*75 

24 

24 

36 

12 

150 

000 

3-50 

30 

33 

40 

12 

200 

000 

4-25 

36 

36 


27. The Waddle fan has deservedly a good reputation, and is 
comparati vely cheap in erection; it will exhaust a large volume 
of air, but runs at a higher speed than the Guibal. The fol¬ 
lowing particulars show the results of observations made on 
the working of one of these fans, 35 feet diameter, at Holmside 
Colliery, Chester-le-Street, County of Durham, England. 


.Revolutions of Fan 
per minute. 

Volume of Air 
in Cubic feet per 
minute. 

Water-Gauge 
in inches. 

Efficiency 
per cent. 

29 60 

83,742 

•777 

66-7 

37-20 

108,777 

1-082 

66-9 

50* 

140,158 

2-07 

65-3 


As it is a rule in ventilation that the quantity of air in mo¬ 
tion is in accordance with the square root of the pressure, or 
the water-gauge, we may apply it to the above results, thus : 

The square root of *777 = ’881 
The square root of 1 082 = 1 04 
The square root of 2‘07 = 1’439 

then if *881 : 83742 :: 1 04 ought to give 98,853, and 1.439 

ought to give 136,782, which figures are different from the actual 
quantities given, but the discrepancies might be occasioned by 



































18 


the reading of the water-gauge in the first quantity being put a 
little too high. Although here the quantities do not come out 
mathematically true, the law of ventilation mentioned is practi¬ 
cally maintained. 

28. The quantity of air passing in a mine is in accordance 
with the square root of the pressure in force. 

The pressure of the ventilation is according to the square of 
the quantity of air passing. 

The power is according to the cube of the velocity. 

The quantity is according to the cube root of the power. 

The volume of air exhausted by a fan is in proportion to the 
speed at which it runs. 

The water-gauge or pressure is in proportion to the square of 
the speed at which a fan runs. 

The power applied to the axle of a fan is in proportion to the 
cube of the speed at which it runs. 

In furnace ventilation, if the same difference of temperature 
be maintained in the down and upcast shafts, the ventilating 
pressure will be according to the depth ; therefore the quantity 
of air to be obtained by furnace will be sensibly proportionate 
to the square root of the depth. 

29. Doubling the velocity of air in roads, without altering 
their dimensions, increases the pressure fourfold, and the power 
eightfold ; the pressure being according to the square and 
the power according to the cube of the velocity. If the veloc¬ 
ity be increased from 4 to 5 feet per second the relative press¬ 
ures will be in the proportion of 16 to 25, and the powers as 64 
to 125, because 4 2 = 16, 5 2 = 25, and 4 3 = 64, 5 3 — 125. 

80. The power necessary for overcoming the friction of air in 
roads increases as the area of the roads diminishes ; thus, 
thirty-two times the power is required to pass the same quan¬ 
tity of air through a road 3 feet square, as one 6 feet square; 
this is carefully worked out in the following table : 


Size of 
air-way 8. 

0. 

d. 

r i i 3 , = 

o i - 
l a J 

Relative 

poAvers, making 
the road. 

6 X 6=-1. 

6X6 

24 

36 

•0005144 

1* 

5X5 

20 

25 

•0012800 

2 29 

4X4 

16 

16 

•0039062 

7 59 

3X3 

12 

9 

*0164608 

32- 

3X3 

8 

4 

T250000 

243* 


From this it will be seen that it is not only difficult to get the 
same quantity of air through small air-ways as larger ones, 
but practically impossible to do so. 

31. The power necessary for overcoming the friction in round 

















19 


shafts increases as the diameter diminishes in an almost incred¬ 
ible ratio; in a 14 foot shaft three and a half times as much 
power would be used up in friction as would be necessary in an 
18 foot shaft. In fact the power required for overcoming' the 
friction of the same quantity of air increases in inverse ratio 
to the fifth power of the diameters of round shafts or air¬ 
ways, 

32. It will be seen that the ventilation of a mine is much 
more easily promoted where the shafts and underground roads 
are roomy, than otherwise—the resistance being greatly in¬ 
creased by the reduction in the size of the air passages—the resist¬ 
ance being in inverse proportion to the square of the area, thus 
a road 16 feet area, will require four times the ventilation 
pressure to pass the same quantity of air as one 32 feet area. 

33. When the underground workings are extensive, each 
district should be ventilated by a separate split or current of 
air, and the foul air of each district conveyed to the main re¬ 
turn, without passing through the workings of another dis¬ 
trict. Splitting the air, is to divide the current into two or 
more currents by allowing it to pass along from one into two 
or more roads. This is equal in effect to increasing the area of 
the original road, and reducing the velocity and consequent 
resistance of the air current. By this means, likewise, a cur¬ 
rent of fresh air is taken into each district, which is thus ven¬ 
tilated separately from the rest of the mine, so that in case of 
an explosion of fire-damp in another district, it has a chance of 
being isolated from the effects of it. 

By Section 7 of Article X of the Anthracite Mine Law of 
1891, “ Every mine employing more than 75 persons, must be 
divided into two or more districts. Each district shall be pro¬ 
vided with a separate split of pure air, and the ventilation 
shall be so arranged that not more than 75 persons shall be em¬ 
ployed at the same time in any one current or split of air.” 
And Article IV., Sec. 2 of the Bituminous Mine Law of Penna., 
1893, provides that: 

“ After May thirtieth, one thousand eight hundred and 
ninety-four, not more than sixty-five (65) persons shall be per¬ 
mitted to work in the same air-current. Provided , That a 
larger number not exceeding - one hundred may be allowed by 
the mine inspector when, in his judgment, it is impracticable to 
comply with the foregoing requirement, and mines where more 
than ten (10) persons are employed shall be provided with a fan, 
furnace or other artificial means to produce the ventilation, 
and all stoppings between main intake and return air-ways 
hereinafter built or replaced, shall be substantially built with 
suitable material which shall be approved by the inspector of 
the district.” 

34. The equal splitting of air, is a matter that cannot practi¬ 
cally be carried out; it can only be done when all the splits 
leave the main intake current at the same place, and join the 


20 


main return together; they must likewise have equal length, 
area and rubbing surface, so as to offer an equal amount of 
resistance. 

If a number of splits leave the main air-current at the same 
place, they will all be subject to the same pressure, but if they 
are of unequal length and area, the friction in each division 
will be different, and consquently the quantity of air passing 
in each current will be different. If a split be made at the pit- 
bottom, the air of that split will have a greater pressure than 
a split made further in towards the workings. Of course, the 
quantity of air in a short split may be reduced by putting in a 
regulator. The quantity of air passing* in different splits.cannot 
but vary, unless they are equalized by regulators, because by 
the nature of mining, they are sure to be of different lengths 
and areas, are not always split at the same place, and conse¬ 
quently not subject to the same amount of pressure—the pres¬ 
sure decreasing as we move along the current in going towards 
the workings. 

35. The pressure on a door or stopping erected between the 
intake and return may be ascertained by inserting* a water- 
gauge through a hole; the difference of the height of the water 
in the two legs of the tube represents the pressure. Supposing 
the two long roads on Fig. 2 represent the intake and return of 
a mine and that they are each six feet square, and that the 
short roads between them are 500 yards apart, and that the 
current is moving at a velocity of five feet per second, it will 
be found by calculation, taking the co-efficient at *00000001 
pound per square foot of rubbing surface for a velocity of one 
foot per minute, that the water-gauge will read at the stoppings 
in the short roads between the intake and return as follows : 


HH> ' he ■ 

.fle- 

- X* 

h 

H 


In lak e 


-► 



Fig. 2. 


At A...- *35 inches of water-gauge. 

At B- *69 inches of water-gauge. 

AtC-1*04 inches of water-gauge. 

At D- 1*38 inches of water-gauge. 

At E. 1*73 inches of water-gauge. 

At F..— 2*08 inches of water-gauge. 


36. A fair velocity for air to travel at in a mine where men 
are working, in an ordinary sized road, is about 4 or 5 feet per 
second. Air should not be split so as to reduce the current 
below a speed of say 3 feet per second. 

37. Although under paragraph 77 of the Theory and Prac¬ 
tice of Ventilating Coal Mines, the writer has recommended 






















that air, in ventilating single places, should be taken in by the 
narrow side, he certainly thinks it will be much more pleasant, 
both in sinking pits or driving tunnels, where there is plenty 
of ventilating pressure, that the air 
be taken down or along the large 
side. By this means the workmen 
can always get to their work bypass¬ 
ing down or along the intake or lresli 
air side, and the powder smoke or 
other foul air will pass away on the 
narrow side, and by this plan there 
is a great advantage in having the 
air in the shaft or tunnel clear so 
that the workmen can have a good 
sight of all around them. 

38. On the question as to which 
should be the intake, the broad or 
narrow side, a German miner, the 
author of Schlagwetter, says: 

“ Where single places are venti¬ 
lated by air tubes, those through 
which the air is blown in should 
have the preference, because the 
air in the small tubes has a greater 
velocity and consequently is more 
efficacious in diffusing the gas. A 
government inspector in Saxony, 

Bergamtsrath Menzel, made several 
experiments at Brackenberg, No. 2 
shaft, Zwickau, by using air tubes, 
and at different times passing the 
air in and out of them, and found 
the quantity of fire-damp two to three times as great when 
the air was drawn out of the tubes as when it was forced in.” 

The opinion of the German authority is here quoted for the 
benefit of the student and practical man, but notwithstanding 
it, and the opinion previously given by the writer in his The¬ 
ory and Practice of Ventilating Coal Mines , referred to in 
the previous paragraph—he is now disposed to say that the 
fresh air should be taken in the large side of a tunnel if it 
be used as a traveling road, and for taking out the dirt by 
a mining car; in very long tunnels or exploring headings he 
has frequently noticed where the contrary mode was practiced 
that the powder smoke remained in the road, so that it was not 
only unpleasant to travel through, but difficult, if not impos¬ 
sible, to put on lines and take sights from them to keep the 
tunnel straight. Fig. 3 shows how a tunnel, the construction 
of which is commenced from the intake road, may be ventilated 
by air-tubes. 

39. Gases lying in the goaves or wastes of a mine being 





-P 1 


Section 

Fig. 3. 



























elastic, are much influenced by the alteration of the pressure 
in the atmosphere. 

Practical miners who are at all observant are well acquainted 
with this fact and notice that the expansion or attenuation of 
the gas in a goaf will indicate a change in the pressure of the 
atmosphere before the barometer does at the surface. The 
barometer is too sluggish in its movements to be of any use as 
a foreteller of the issue of fire-damp in a mine ; gas as an indi¬ 
cator of atmospherical changes is much more sensitive than the 
ordinary barometer—indeed, it shows the changes of pressure 
itself more readily than anything else, it being lighter than 
any other body. Indeed, it has been found by observation that 
variations in the reading of the barometer do not indicate ap¬ 
proaching increase of gas in a mine, the gas being more rapid 
in its movements than a barometer at the surface, and that the 
increase of gas in a mine will indicate the approach of a storm 
many hours before the barometer is moved. (See page 50, Vol. 
II of Transactions of the Federated Institution of Mining En¬ 
gineers.) The volume of a gas varies inversely as the pressure 
upon it, and the density and elastic force are directly as the 
pressure and inversely as the volume. If the atmospheric 
pressure decreases, the gas contained in a gob, goaf, or other 
cavity will expand and make its exit into the adjacent roads. 

40. Repeated experiments at Karwin have proved in the most 
convincing manner that by an artificial and rapidly produced 
rarefaction of the air of the mine, there is a considerable in¬ 
crease in the issue of gas, especially from the gobs or wastes. 

41. Roughly speaking, mercury is thirteen and a half times 
heavier than water, 11,000 times heavier than air, and 20,000 
times heavier than fire-damp ; it is well for the miner to re¬ 
member this, as the pressure indicated by a variation of 1 inch 
of the barometer is represented by a very large body of fire¬ 
damp. 

42. Blowers or sudden outbursts of gas appear to occur inde¬ 
pendently of meteorological vicissitudes. In order to give those 
readers who have no knowledge of blowers an idea of what 
those outbursts are, the following paragraph is quoted from the 
Final Report of the Royal Commission on Accidents in Mines 
(Great Britain), page 23: “Numerous sudden outbursts have 
been described, especially those at the colleries of Walker, 
Jarrow, Has well and Hebburn, in which the eruption of gas was 
accompanied by the dislodgment of large quantities of coal, 
much of it in a disintegrated state (known as ‘ dantywal ’). The 
clear description by Mr. G. Clark of two such cases which oc¬ 
curred in November and December, 1846, from the low main 
coal at Walker Colliery records that in approaching a slip dike 
a quantity of small coal amounting in one case to eleven tons 
was violently projected into the workings, accompanied by a 
discharge of gas,which in the course of a few minutes fouled,"re¬ 
spectively, 41,000 cubic feet and 86,000 cubic feet of the air pas- 


sages. So good, however, was the discipline, and so prudent 
the behavior of those present, that although a terrible explo¬ 
sion seemed imminent and several of the Davy lamps became 
red hot, no accident happened.” 

43. It is believed that there is some connection between 
earthquakes, the issue of gas in coal mines, and the occurrence 
of colliery explosions. Dr. Rudolph Falb, a German Philoso¬ 
pher, holds this opinion : “ His theory is that the inner portion 
of the earth must be regarded as liquid, and that the fluid of 
the interior is drawn by the attraction of the sun and moon into 
the cracks and channels of the earth’s crust; when cooling 
takes place, explosions of gas occur, and subterranean volcanoes 
become extinct.” 

44. Professor Milne, the author of Earthquakes and other 
Earth Movements, does not believe that the changes of the 
barometer have any marked connection with the occurrence of 
earthquakes in Japan at least, where so many of these terrible 
occurrences take place. He says, however, that the phenomena 
of the emission of steam from Stromboli and noises from the 
volcano of Vulture, occurring as they do on certain changes 
of the weather, have a direct relationship to barometrical 
pressure. 

45. Blasting with gunpowder in dry and dusty mines may 
cause serious disasters in the entire absence of fire-damp, and 
there is no doubt that the presence of fine coal dust in a mine 
very much exaggerates the force of an explosion ; indeed, it is 
said that all dust, not only the dust of pure coal, is more or less 
dangerous. 

454- Before a shot is fired, a careful search should be made 
to ascertain whether fire-damp is present or not. The opera¬ 
tion should not be carried out w r here the ventilation is not 
sufficient to render the gas harmless. In fiery mines, and those 
which have much coal dust, the practice of shot firing should 
be limited as much as possible or prohibited altogether. By 
Rule 33 of An Act relating to the Bituminous Coal Mines of 
Penna., approved May 15th, 1893, it is provided that: “ When 
a workman is about to fire a blast he shall be careful to notify 
all persons who might be endangered thereby and shall give 
sufficient alarm so that any person or persons approaching shall 
be warned of the danger.” 

46. Return air as a rule is lighter than intake air ; on this ac¬ 
count it is better where practicable to take return air upwards 
rather than otherwise. In the coal mines of Westphalia where 
the seams frequently lie at a steep angle, as shown in Fig. 4, the 
usual way is to carry the air in the first place to the lowest 
working level of the colliery and pass it up to the upper levels, 
and eventually to the return airway—the air being conducted 
ascensionally through the mine. By this mode the ventilation 
pressure is increased, without the expense of applying artificial 
means, but simply by utilizing this natural law, so that where 


24 


tiie temperature of the intake is 50° and the return is 95° an ad¬ 
ditional pressure of over 5 lbs. per square foot is obtained— 
nearly equal to one inch of water gauge—where the rise work¬ 
ings are 800 feet above those of the deep. 



47. Shallow pits are more difficult to ventilate than deep 
ones, because with them you cannot get so great a ventilating 
pressure as by deep shafts. 

48. The ventilation of deep mines is less affected by changes 
of the weather than that of shallow ones; as the mine increases 
in depth so does the temperature, and consequently the ven¬ 
tilating pressure. 

49. In England it has been noticed that a south wind is un¬ 
favorable to the ventilation of shallow mines ; on the contrary 
a north wind is favorable. 

50. Changes of the weather do not materially affect the cir¬ 
culation of air in any mine where proper artificial means of 
ventilation are provided. 

51. Dip workings in a mine are more easily ventilated than 
rise places. 

52. Air always takes the short-cut when under pressure, and 
without pressure there will be no current. 

53. Narrow places, especially in fiery mines, should not be 
driven in advance of the air current. 

54. Good ventilation and a good light will tend much to the 
safety of all engaged in mining operations. 

55. Notwithstanding the law of diffusion of gases, it is gen¬ 
erally found, that the lighter gases remain in the upper part, 
and the heavier gases in the lower part of a mine. There is 
great difficulty in mixing atmospheric air with inflammable gas. 

























56. Walling back gas, should not be practiced ; when a dis¬ 
used road is abandoned it is better to till it up altogether, or 
pass a current of air through it; many explosions have oc¬ 
curred by stoppings and dams in such cases having proved im¬ 
perfect, through which the gas has escaped and come onto naked 
lights. According to Art. V., Sec. 1., of An Act relating to the 
Bituminous Coal Mines of Penna., the law is that : “ All mines 
generating fire-damp shall be kept free of standing gas in all 
working places and roadways. No accumulation of "explosive 
gas shall be allowed to exist in the worked out or abandoned 
parts of any mine, when it is practicable to remove it, and the 
entrance or entrances to said worked out or abandoned places, 
shall be properly fenced off, and cautionary notices shall be 
posted upon said fencing, to warn persons of danger.” 

57. Stoppings put in rise places, should be placed at or near 
the lower end, next to the intake current; this prevents an 
accumulation of gas on the lower side of the stoppings, which 
might come in contact with naked lights, which are generally 
used in the intake. 

58. The best safety lamps afford no protection when handled 
imprudently, and there are many conditions when some of the 
so-called “safety lamps” are dangerous, particularly the 
Clanny and Davy, which have been exploded in an inflammable 
mixture passing at the rate of 8 feet per second. By Art. V., 
Sec. 6, of the Act relating to the Bituminous Coal Mines of 
Penna.: “ The use of the common Davy safety lamp, for gen¬ 
eral work in any Bituminous coal mines, is hereby prohibited, 
neither shall the Clanny lamp be so used, unless its gauze is 
thoroughly protected by a metallic shield, but this Act does 
not prohibit the use of the Davy and Clanny lamps by the 
mine officials for the purpose of examining the workings for 
gas.” 

59. Workmen should not be allowed to ramble about a mine 
from one place to another. General Rule 71, of the Bitumi¬ 
nous Coal Mines Act of Penna., approved May 15,1893, provides 
that: “ No person or persons shall go into any old or aban¬ 
doned parts of the mine, or into any other place which is not 
in actual course of working, without permission from the mine 
foreman, nor shall they travel to and from their work except 
by the traveling way assigned for that purpose.” 

60. Wafting or brushing gas away should not be allowed— 
the gas should be removed by a current of air. According to 
General Rule 66, of the Bituminous Coal Mines Act of Penna.: 
“ An accumulation of gas in mines, shall not be removed by 
brushing.” 

61. It is the opinion of the writer, in which he is supported 
bv many mining authorities, that mixed lights should not be 
used in a mine—that is to say, safety lamps in one part and 
candles or other naked lights in another part. 

62. In all cases of an explosion, it is a good plan, if a man 


26 

has sufficient notice, to throw himself upon his face until the 
blast passes over him, and as soon as he is satisfied that it is 
over (it is frequently repeated at the interval of a minute or 
two) let him calm his fears as much as possible, and make his 
way out toward the fresh air. This was a recommendation of 
the late Mr. Matthias Dunn, one of the original inspectors of 
mines in England. 

63. In all cases where fire-damp accumulates, it is important 
that no attempt should be made by the workmen to remove it, 
except under the direction of some responsible person; care 
being taken that the foul current in passing along the return 
side towards the upcast, shall not endanger the lives of any 
workman who may be engaged there. 

64. Special care should be taken for fear of an accumulation 
of gas when the pit commences work, after Sundays or holi¬ 
days. This admonition is made because accidents have fre¬ 
quently happened through the ventilation having become dis¬ 
arranged during the suspension of coal working. From this 
we might expect Monday to be the most dangerous day of the 
week as regards explosions of gas, and since making this note 
the writer has been confirmed in that view by the publication 
of the report of the Prussian Fire-Damp Commission, from 
which it appears that of 1,666 explosions which occurred, 
they took place, according* to the days of the week, as follows : 


Sundav.......44 

Monday......327 

Tuesday. .273 

Wednesday__ 240 

Thursday_ 271 

Friday_ 259 

Saturday_ 252 


65. Ventilation plans showing, by arrows, the course of the 
air currents, and by a variation in color the different splits, 
should be kept regularly up to date. By Art. I., Sec. 1, of the 
Bituminous Coal Mines Act of Penna., the map or plan of a 
coal mine shall show “ By darts or arrows made thereon by a 
pen or pencil the direction of air currents in the said mine.” 

66. In Great Britain, the lives lost by explosions of fire-damp 
form 21 per cent, of the total number lost at collieries ; the 
number lost by falls of roof and sides is 40 per cent, and by 
miscellaneous accidents 39 per cent, over a series of years. In 
the Anthracite Coal Mines of Pennsylvania in 1891, the per¬ 
centages of accidents were as follows : 

Explosions of gas______ 8*88 

Falls of roof and coal_ ___39‘72 

Miscellaneous _ r , __51 *40 


100-00 













O* 


In the Bituminous Mines the percentages work out as fol¬ 
lows : 


Explosions of gas_ __ 50-00 

Falls of roof and coal___ _ 3198 

Miscellaneous ........18-02 


100-00 

67. There are a number of different gaseous mixtures that 
are, under certain conditions, explosive—for example, light 
carbureted hydrogen, olefiant gas, coal gas, carbonic oxide, 
sulphureted hydrogen, some sewer gases and other emana¬ 
tions ; and there appears to be no doubt that dust of flour will 
also explode under particular circumstances. A flour dust ex¬ 
plosion occurred on the 21st of March, 1S93, at the Keeler flour 
mill, Litchfield, Ill., when the immense structure was blown to 
fragments. The nature and composition of the explosive gases 
given off in mines vary very much. Fire-damp is very often 
written about and spoken of as being pure carbureted hydrogen, 
whereas it is often mixed in varying proportions with other 
gases. An c ygas that will explode may be considered fire-damp. 
In the practical working of mines, and by experiment, it has been 
found that dry atmospheric air with an admixture of coal dust 
is explosive, and by General Rule 60 of the Bituminous Coal 
Mines Act of Penna., it is provided that “In mines where coal 
dust has accumulated to a dangerous extent, care shall be ex¬ 
ercised to prevent said dust from floating in the atmosphere by 
sprinkling it with water or otherwise as far as practicable.” 

68. Miners may be suffocated by going into fire-damp by the 
inhalation of the gas, without an explosion taking place. In 
the evidence given before the Royal Commission on Accidents 
in the Mines of Great Britain by Mr. Dickenson, he said that 
people were occasionally suffocated by fire damp, and further 
on that “fire-damp can suffocate as well as black-damp if you 
have it strong enough.” 

69. Carbonic acid gas, or carbon dioxide ( C O a ) is often met 
with in coal mines—particularly shallow mines; its chemical 
composition by weight is oxygen 72-73 per cent., carbon 27 - 27; 
its specific gravity as compared with air is 1’525—it is poisonous, 
and is dangerous to breathe when it is contained in the air to 
the extent of 8 per cent., and lights will not burn in air contain¬ 
ing 10 per cent of it. When lig-hts are extinguished by it, it is a 
warning that the air is contaminated with it to such an extent 
as to render it highly dangerous to breathe. It is given off by 
the respiration of animals, combustion, fermentation, decay of 
vegetable matter and volcanic emanations. 

70. Carbonic oxide, or carbon monoxide (C O) is composed 
by weight of 56*69 percent, of oxygen, and 43-31 of carbon, and 
its specific gravity is -975, air being 1. This gas has a far more 
deleterious effect on the animal system than carbonic acid ; for 






if atmospheric air be mixed with 1 per cent, of it, the breathing* 
of it is fatal, whilst, at the same time, a lamp will burn in it. 
It is found where gob fires exist, and is the result of incomplete 
combustion. It is inflammable, and as the late Mr. Henry John¬ 
son stated in his evidence before the Royal Commission on 
Accidents in the Mines of Great Britain—“ explosions from 
spontaneous combustion are due to a certain admixture of at¬ 
mospheric air with carbonic oxide.” It is a colorless, invisible 
gas, without taste or smell, and burns with a bright blue flame. 

71. Carbureted hydrogen or methyl hydride (C H 4 ) has a 
specific gravity of *555, and is composed of 24*6 per cent, by 
weight, of hydrogen, and 75*4 per cent, of carbon. It is highly 
explosive when mixed with certain proportions of air ; when 
present to the extent of one part to thirty parts of air, by 
volume, it may be detected by the flame of a candle, and 4 per 
cent, will show a blue cap on the flame of a safety lamp. It has 
hitherto been considered that 7 to 14 per cent, of this gas 
mixed with air is the maximum of explosibility, but probably 
a very much smaller percentage is sufficient to cause an ex¬ 
plosion in some mines. The carbureted hydrogen of mines is 
found to be mixed with various proportions of other gases, and 
that of one mine is frequently very different from that of 
another mine. 

72. Olefiant gas, called likewise heavy carbureted hydrogen, 
or ethylene, has the chemical symbol C 2 H 4 , and a specific 
gravity of *9784. It is composed of 2 atoms of carbon and 4 
atoms of hydrogen, and is produced by the distillation of coal 
and carbonaceous matter. It is a colorless, invisible gas, pos¬ 
sessing a sweetish taste, and burns with a brighter flame than 
marsh gas. 

73. Suiphureted hydrogen, or hydric sulphide, known by the 
symbol H 2 S, is composed by weight of 94*15 per cent, of 
sulphur and 5*85 per cent, of hydrogen. Its specific gravity is 
1*19, air being 1. 

It is a colorless gas having a smell, by which its presence is 
easily detected, of rotten eggs. It is inflammable, and burns 
with a pale bluish flame. It is met with in coal mines, and is 
evolved from volcanoes. It occurs also in solution in many 
mineral springs, such as those of Harrowgate in Yorkshire, 
England. 

74. Sulphurous acid gas has been found in the air of Cornish 
mines and elsewhere; it is one of the products of blasting. It 
is frequently found in the water, which occasionally contains 
sulphuric acid, as is the case in some furnace shafts. 

75. An explosion of fire-damp renders ten times its bulk of 
air unfit for respiration, and this vitiated atmosphere, called 
after-damp, is very deleterious and causes more loss of life than 
the explosion itself. An explosion destroys the oxygen in 
the air and produces carbonic acid, carbonic oxide, steam and 
nitrogen, all of which are unbreathable. 


It has been calculated that an explosion of carbureted hydro¬ 
gen and air will exert a pressure of 210 lbs. on the square inch, 
which is equal to 162 tons on the square foot, but by experi¬ 
ment it is found that the extent of its effects on the workings 
of a mine depends very much on where the gas is fired. 

76. Gob fires or spontaneous combustion of coal in goaves 
take place through leaving large accumulations of slack, or 
small coal, in the mine, and they are more frequent in thick 
than in thin coal seams. The thicker the coal lies on the floor, 
and the damper it is, the quicker it fires. The primary cause 
of gob fires in the Dudley, England, thick coal is not attributed 
to the presence and oxidation of iron pyrites, but it is con¬ 
sidered that spontaneous combustion takes place through the 
action of oxygen upon the finely divided coal. The seam of 
coal in South Staffordshire, England, which contains the lar¬ 
gest quantity of iron pyrites—namely the stinking coal, is not 
liable to spontaneous combustion. Mr. Henry Johnson said 
before the Royal Commission on Accidents in Mines in Great 
Britain that “the more impure the coal, the more rapid the 
spontaneous combustion. A hard, bright coal will produce 
less gob fire than soft impure rubbishy coal.” Gob fires, which 
are almost unknown in the deep coal, have frequently taken 
place, in fact, are of common occurrence in the shallow coal of 
the Cannock Chase district, Staffordshire, and it is a noteworthy 
fact that more such fires occur during slackness of trade than 
at other times, more small coal being left in the gob, and the 
working face not advancing so rapidly then. The reason there 
are more fires in the “ shallow ” than the “ deep ” may be that 
the shallow is a more volatile coal and likewise contains more 
dirt. To prevent such fires the slack should not be allowed to 
accumulate. Gob fires are not known in the Anthracite mines 
of Great Britain or America. 

77. Natural gas exists in the earth in large quantities, under 
great pressure and at considerable depths. In various parts of 
England, Scotland and Wales, the gas escaping from the coal 
measures has at different times been utilized at the surface for 
the purpose of lighting. The holy fire at Baku in Persia, which 
has been burning for centuries, is due to the issue of carbureted 
hydrogen mixed with small quantities of nitrogen, carbon 
dioxide and petroleum vapors. The gas issuing from the mud 
volcanoes of Balganek, in the Crimea, according to Professor 
Bunsen, consists of pure carbureted hydrogen. The largest 
supply of natural gas hitherto met with is that in the United 
States of America, in parts of Pennsylvania, Ohio, New York, 
Illinois, and Indiana, where it is now extensively used for 
lighting and manufacturing purposes. In Pittsburg, the Ameri¬ 
can Birmingham, natural gas has been used for many years on 
a large scale for lighting, working and heating. Although 
natural gas was known in the town of Findlay, Ohio, for a long 
time—a German physician named Dr. Aesherlin, having lit up 


30 


all the rooms of his house with it for thirty years—it was not 
until 1887 that public interest was aroused in the matter, and 
bore-holes put down to ascertain the extent of the supply, and 
the depth and pressure at which it existed. The first hold 
tapped a feeder of gas amounting to 150,000 cubic feet per day, 
which when lit up, could be seen at night 15 miles round. 
Later a deeper hole was bored, which had to pass through a 
thickness of 350 feet of Trenton limestone ; this yielded at a 
depth of 1,200 ft., 1,206,000 cubic feet of gas per day, but this 
great yield was exceeded by other holes put down afterwards. 
At the present time there are over twenty bore-holes in and 
around Findlay, all of which are yielding large quantities of 
gas; four of the most fertile in supply yield respectively 
12,080,000,-3,318,000,-2,565,000, and 1,159,000 cubic feet daily. 
The chemical composition of this gas is: 


Marsh gas.......92 61 

Petroleum vapors__ '30 

Hydrogen_ 2'08 

Oxygen_ 3 61 

Nitrogen____... '34 

Carbonic acid ,_ *26 

Carbonic oxide. '50 

Sulphureted hydrogen__ '30 


One hundred cubic feet of the gas contain 125*8 grains of 
sulphur. The weight of a cubic foot of gas is 318 98 grains. 
The average pressure of the Findlay natural gas is 375 lbs. per 
square inch. The quantity of natural gas which issues from 
bore-holes, appears to diminish, and the pressure gets less as time 
goes on. According to a recent report of the Indiana State 
Geologist, the pressure of the gas in the Indiana field was at 
first 325 pounds to the square inch, but it has in some cases de¬ 
creased to 60 pounds. Many of the holes are entirely useless, 
some because the gas supply is exhausted, and others on ac¬ 
count of the presence of salt water. The field in the immediate 
neighborhood of Kokmo is entirely exhausted. The greatest 
pressure in the Anderson Field is 325 pounds. The State 
Geologist of Illinois, in referring to the natural gas deposited 
there, gives it as his opinion that it did not originate in the 
olden formations of the Devonian and Silurian, from which the 
main supply of this material is obtained in Ohio and Pennsyl¬ 
vania, but had been generated in one of the old peaty soils, 
which are interstratified with the drift clays, and are found 
intact over extensive areas in Illinois. 

78. The issue of natural gas has in more than one instance 
been the means of setting a river on fire. A small river known 
as Catfish Run, in the petroleum regions of Pennsylvania, has 
for years been covered with bubbles. These, on bursting, emit 
a strong smell of gas. On one occasion some visitors to the 
neighborhood, by way of experiment, saturated a bunch of 










rags with oil, set fire to it, and allowed it to float down the 
stream. The flame ignited the gas, and an explosion followed. 
In a few moments the body of the gas burned steadily, and 
from eveiw portion of the surface of the water small flames 
sprang up, when the gas escaped in moderate quantities. It is 
said the gas has continued to burn ever since, and at night the 
effect is magnificent. A similar phenomenon has been wit¬ 
nessed on the River Wear at Framwellgate, near Durham, 
where fire damp issuing from the coal mines has been seen to 
burn for some time. 


CHAPTER II. 

EXPLANATION OF TERMS USED IN THE SUBJECT OF MINE VEN¬ 
TILATION. 

Aerophore. —The name given to an apparatus which will 
enable a man to enter places in mines filled with explosive or 
other deadly gases, work there with freedom, take with him a 
light, and remain for an indefinite time. (W. S. Gresley.) 

After-damp .—A noxious mixture of gases resulting from 
an explosion of fire-damp. It has always been impossible to 
make an exact analysis of the-after-damp from an actual ex¬ 
plosion, but one result of it is to use up the oxygen of the air 
and to produce carbonic acid and steam, as well as sometimes 
carbonic oxide, which with the nitrogen, make the mixture un- 
breathable. Carbonic oxide or carbon monoxide is not usually 
present in after-damp, but from certain explosions, in which 
coal-dust has formed part of the combustible material, it has 
been found to exist. 

Air-course. —A road constructed and kept open for the air 
to pass along. 

Air-crossing. —A place in the mine where one current of air 
passes over another ; such a crossing is often made by build¬ 
ing walls on each side of the lower road, and laying planks 
across from one side to the other ; it is sometimes formed by 
arching with masonry, by iron tubes, or otherwise; or it may 
he made by driving in the solid rock one road over or under the 
other. 

Air-pipes .—Tubes or boxes for air to pass through to ven¬ 
tilate a single underground road. 

Air-troughs. —The same or similar to air-pipes; they are 
made of different materials, wood, iron, earthenware, or can¬ 
vas ; when made of the latter material, they are kept open by 
iron hoops being placed inside at intervals. 

Anemometer. —An instrument used to ascertain the speed at 
which air flows through a mine, which may easily be read on 
the face of the instrument. It is liable to get out of order 
through coal dust and damp, and should occasionally be tested 





and rectified. The quantity of air passing per minute in an air 
road may be ascertained in this way : Measure tlie size of the 
road, and read off the number of revolutions made by the 
anemometer in a given time, say a minute, then multiply the 
area of the road in feet by the speed, this will give the cubic 
feet of air passing per minute. If the velocity of the air be 
400 feet per minute, and the road measures 8 feet by 6 feet, 
then the quantity of air passing per minute will be 19,200 cubic 
feet. 

Area. —The superficial measure of anything, as for instance 
the section of an air-passage, which is obtained by multiplying 
the height by the width. If a road measures 7 feet high and 9 
feet wide, then its area is 7 X 9 = 63 sq. ft. 

Artificial Ventilation. —The means put in force to produce a 
current of air. The way this is done is by altering the density 
of one end of the air-current. For this purpose sometimes the 
furnace is used and sometimes the fan. By the action of the 
furnace the air. at the outlet end of the column, is heated and 
consequently made lighter or more attenuated, towards which 
the colder air, at the other end of the column, flows. By the 
action of the exhausting fan, a vacuum is formed, into which 
the air from the mine passes so long as the machine is kept in 
motion. 

Ascensional Ventilation. —The principle of coursing the air, 
after it has descended or entered the mine, through the work¬ 
ings in an upward direction. Mine air beingusualty lighter than 
the outer air, will naturally tend upwards. To carry the prin¬ 
ciple out fully, the upcast shaft should be placed on the rise or 
crop side of the workings. Of course, in flat-lying seams the 
principle does not apply. 

Asphyxia. —This is a word used by members of the medical 
profession, and is frequently found in the reports of mine in¬ 
spectors. It signifies a lowering of the pulsation, but is gen¬ 
erally used to mean a total cessation in respiration, caused by 
the prevention of the entrance of pure air to the lungs. This 
condition of the human body is caused by inhaling after-damp 
and other mixtures of noxious gases ; asphyxia .will result 
from the breathing of carbonic oxide, carbonic acid and, in 
some cases, fire-damp. 

Atmosphere. —The air which surrounds this spheroidal earth 
of ours, and which is composed of a mechanical mixture of 
oxygen, about one-fifth; and nitrogen about four-fifths. Sev¬ 
eral properties of the atmosphere are described under para¬ 
graphs 1 to 11, in Chapter I. 

Bag. —As referring to fire-damp, it means a small quantity 
of gas given off from a coal-seam, or a small quantity lying up 
in a hole in the roof. 

Barometer. —An instrument used for measuring the pressure 
of the atmosphere. It is constructed in various forms, but the 
best and most practical is a straight tube of glass sealed at one 


Gncl so as to be quite air-tight; when this is filled with mercury 
the open end is closed with the thumb, and it is inverted into a 
cup of mercury. The mercury in the tube will then descend 
until its weight just balances the pressure of the atmosphere. 
The upper surface of the mercury will rise and fall according 
as the pressure of the air varies, and this is measured by a scale. 
The barometer may be used for finding depths of shafts—near 
datum of sea level—by the following rule : 

26216 X I, 

D =-, and 

R 

DXB 

I —-= difference of reading of barometer at 

26216 

top and bottom of shaft, 

where I = inches of mercury due to depth of shaft, 

D = depth of shaft in feet, 

B = height of barometer at pit top. 

Barometer Holiday .—A term used in Derbyshire to signify 
an idle day at the mines, occasioned by the barometer being 
low—perhaps down to 29 inches and which affects the ventila¬ 
tion by causing an accumulation of gas. 

Black-Damp .—The name given to carbonic acid gas when 
found in a mine. It is a very heavy deadly gas, and when a 
candle is put into it the light goes out and the wick is left quite 
black—hence probably the name. 

Blower .—A sudden eruption of fire-damp into the working's 
of a coal mine. Unexpected issues of explosive gas have fre¬ 
quently taken place in deep coal mines of different coal fields, 
and considering the immense pressure at which gas is con¬ 
tained in the coal-seams, it cannot be argued that they are due 
to a reduction in the atmospheric pressure. They often occur 
in working-faces, and sometimes with such force as to baffle 
the ventilation and put the mine in a very dangerous condi¬ 
tion. When this is the case a current of air in sufficient quan¬ 
tity to dilute the gas should be passed through the place where 
the gas issues, in order to render it harmless, and the work¬ 
men should be withdrawn on the return side of the issue. 
Although it may be said that in most cases the gaseous mix¬ 
tures coming off at blowers are made up chiefly of methane or 
carbureted hydrogen, they are frequently composed of vary¬ 
ing proportions of air and the several kinds of gases. Some¬ 
times the issue is chiefly carbonic acid, and at other times it is 
chiefly oxygen and nitrogen. 

Blower likewise signifies a fan used for forcing air into a 
mine. 

Blow George .—The name given in Somersetshire, England, 
to a small mechanical blower or ventilator used for blowing 
air into single roads underground. 




u 


Bloxv-out. —A blast throwing out the tamping without bring¬ 
ing clown the rock or coal. 

Blown-out-shot, —This word is commonly used in England 
to signify the same thing as the word “ Blow-out " does in 
America. 

Boyle and Mariotte's Laic. —The law relating to the dilata¬ 
tion of gases, which is this : The volume occupied by a gas is in 
inverse ratio to the pressure under which it exists, if the tem¬ 
perature remains the same, or the density of a gas is propor¬ 
tional to its pressure, so that air under the pressure of three 
atmospheres will occupy only one-third the space it occupied 
under the pressure of one atmosphere. If the temperature 
be increased, and the air occupy the same space, the pressure 
will be increased, but if the pressure remains the same, the air 
will occupy a larger space. 

This property of the expansion of ah 1 explains the phenome¬ 
non of bursting a bladder by holding it by the fire ; the inter¬ 
nal space of the bladder being limited, the pressure of the air 
increases with the temperature until the limited strength of 
the bladder can no longer resist it and an explosion occurs. 
Air may be compressed so as to occupy only one-thousandth 
part of its original space, or it may be so much expanded as to 
Hll two thousand times the area of the original volume. The 
co efficient of expansion, or increase in the volume of air for 
each additional degree of heat on the Fahrenheit scale, is equal 
to *002039. 

Break-through .—An opening through a pillar for the passage 
of air. 

Breather .—An apparatus constructed to enable a man to 
breathe in impure air. It consists of a reservoir charged with 
oxygen gas, fitted up with a mouth-piece and tube. 

Breeding-fire. —Same as Gob fire. 

Brush. —To dash away a body of gas with a cloth, such as a 
jacket or waistcoat; but to remove gas in this way is against 
the law, as is mentioned in par. 60, Chap. I. 

Cap. —The halo on the top of a flame. Fifty years ago, and 
prior to that time, it was a very common thing for the overmen 
and deputies of the North of England mines to try the candle 
for gas, by first snuffing the wick and lowering the flame as 
much as possible, and then placing the hand before it, and 
gradually raising it to see if it showed any cap. The cap or 
halo formed on the top of a light by carbureted hydrogen is 
blue, and by this means it used to be detected. In examining 
a mine, or in trying or searching for fire-damp, a naked light 
should not be used, but a safety-lamp. 

Carbonyl sulphide. —(C O S). A dangerous compound, which 
is easily inflammable. It is supposed that this gas was present 
in a sample from a blower at Friedenshoffnung Colliery, in 
Germany. 

Centigrade. —The word means to be divided into hundredths. 


The term is applied amongst other thing’s to the thermometer, 
when the distance on the scale between the freezing' point and 
boiling- point is divided into one hundred equal parts. This is 
the scale mostly used for thermometers on the Continent. 
(See Thermometer.) 

Clanny .—The name given to the safety-lamp designed by 
Dr. Clanny of Newcastle-on-Tyne. He altered the construction 
of the Davy, by replacing part of the gauze with glass, by 
which a better light was obtained. With many it is a favorite 
lamp as now constructed in its improved form. 

Co-efficient of friction .—The quantity or number used as a 
multiplier representing the pressure for overcoming the fric¬ 
tion of air, at a given velocity, in rubbing against a given area 
of surface of an underground channel, in passing along it. For 
a velocity in the air of 1000 feet per minute, the friction may be 
taken to be equal to ’12387 feet of air column of the same 
density as the flowing air, which is equal to a pressure qf O’Ol 
per square foot of area of section. There are various estimates 
of the value of this factor. M. Murgue in his recent exhaustive 
experiments on the friction of air in mines, conducted with 
great care, and during which the most delicate possible tests 
were made, found that in 

(1) Brick-lined arched gangways the co-efficient was *001743 

(2) Unlined rock gangways “ “ “ “ *004965 

(3) Timbered gangways “ “ “ “ “ *00842 

The highest of these being *00842 makes the co-efficient 0*01 a 
safe one, and one that makes calculations easy. 

Compressed air .—This is sometimes used as a motive power 
in mines, although it is an expensive one. It has no bearing* on 
ventilation, excepting that the exhaust has the effect of improv¬ 
ing the ventilation (in an inappreciable degree in well ventilated 
mines) and the pipes through which the air passes help to cool 
the mine. 

Coursing of air .—In the earlier days of coal mining, in the 
coal-field of Northumberland and Durham, before splitting air 
was practiced, it was usual to take the air through the pillars 
up two or three boards (or rooms) and down two or three 
boards ; this was called “ coursing two and two,” and “cours¬ 
ing three and three.” 

The proper meaning of coursing the air now, is to cause it to 
move through every space in the mine—especially any place 
into which a man can travel, or which may be approached by 
a light—so that noxious gases are removed, and liability to ex¬ 
plosions of them, or suffocation from them, prevented. In all 
cases a provision should be made for carrying* the air—or 
coursing the air—into every advance heading or excavation, 
whether it be made horizontally, obliquely, or vertically. 

In sinking pits from the surface, they are easily ventilated 


36 


by connecting' the bottom with the chimney of the boiler fires 
with air pipes. 

In the coal mines of Great Britain many accidents have oc¬ 
curred in sinking’ below working- levels, by explosions of gas, 
in consequence of the air not having been carried down as 
sinking progresses. This may be done in a very simple man¬ 
ner, as illustrated by the annexed plan and section Fig. 5. 


Upcast 


—- 

— o — 


n 1 - 

Downcast 

s 


- — 

0) — — 






&= - S 

Bottom of 

1 

Sinning Pit. 


Fig. 5. 


All that is required to be done is to pass a line of air-pipes 
from near the bottom of the shaft to the return air-way as 
shown in the annexed sketch. 

Cube Root .—The common factor of a cube number. Thus 4 
is the cube root of 64. A cube number in arithmetic is that 
which is produced by multiplying a square number by its root. 
Thus, 8 is a cube number and arises by multiplying 4, the 
square of 2, by the root 2. 

Damp .—Carbonic acid gas. (South Staffordshire.) 

Davy .—The name given to the safety lamp invented by Mr. 
Humphrey Davy, afterwards Sir Humphrey. The “ Davy” is 
an ordinary lamp with the flame enclosed by wire gauze. The 
explosive gas, when present, passes through the gauze into 
the cylinder of the lamp and burns inside, giving warning to 
the miner of its presence, but the flame is unable to pass 
through the gauze. “ These facts depend upon the conduci¬ 
ng power of metallic gauze, in virtue of which the heat of the 






































37 


(lame is rapidly dissipated at the points of contact, the result 
being- a diminution of temperature sufficient to prevent igni¬ 
tion. ” ° 

Dead Air.—-The air of a mine is said to be dead or heavy 
when it contains carbonic acid gas (black-damp), or when the 
ventilation is sluggish. 

Door .—A door erected in a traveling passage to prevent the 
air going along it. These erections are of different kinds, as: 

1. Flap-Door .—A man-hole door. 

2. Fly-Door .—A. door erected to open either way, when 
pushed from either side, but which will always of itself swing 
to. 

The annexed sketch, Fig. 6, shows an example in the appli¬ 
cation of a fly-door, which the writer remembers was com¬ 
monly in use over forty years ago, in the coal mines of the 





Fig. 6. 


northern coal field of England. The door was placed in. the 
headways, at each hoard-end —brattice was erected up to the 
face, and the air flowed in the direction of the arrows. 

3. Sheth-Door .—A door used for coursing the air backwards 











































38 


and forwards through old workings of the pillar and stall 
system of the North of England. 

4. Main-Door. —A door placed in a proper frame erected for 
the purpose; it is made to open in one direction—against the 
current. It is put up in a road to prevent the air. going that 
way, and force it through another district. 

5. Man-Door. —A door 18 inches or 20 inches square, pro¬ 
vided with lock and key, placed in a short road between the 
intake and return for the repairman or other official to pass 
through ; such doors are usually in pairs, so that when one is 
open the other is shut. 

6. Separation-Door. —A main-door put up between the bot¬ 
toms of the down and upcast shafts ; they are frequently in twos 
and sometimes in threes, a few yards apart, so that in passing 
through one at a time there is no chance of the air taking the 
short cut to the upcast. 

Downcast. —The name given to the shaft or slope through 
which the fresh air flows down into the mine. 

Drag. —The name given to the resistance met with by the 
air in passing along the underground channels. The amount 
of drag or pressure is generally measured by the water- 
gauge. 

Dumb-Drift. —A sloping road made from the return air- 
course into the upcast shaft which it enters at a sufficient 
height above the furnace to prevent the air, should it be in¬ 
flammable, from exploding. 

Ethane. —(C 2 H' 6 ). This gas, according to the report of the 
Prussian Fire-Damp Commission, has been found in a number 
of blowers. It is likewise said that the gaseous mixtures known 
as propane (C 3 H 8 ) and catylene (C 4 H 8 ) have been detected in 
coal, and that these two gases may be regarded as produced by 
the decomposition of marsh gas and ethane. 

Equivalent Orifice. —The air in passing through the work¬ 
ings of a mine meets with a certain amount of resistance ; this 
is represented as being equivalent to the air passing through 
an orifice in a thin plate of such an area that the resistance 
offered to the entrance of the air would be equal in amount to 
that offered by the underground workings. In other words the 
resistance of a mine which requires a certain water-gauge or 
pressure for the production of a certain volume of air is 
equivalent to an orifice in a thin plate which requires the same 
water-gauge to pass the same volume; M. Murgue, the French 
engineer, assimilates the passages of every mine to an orifice 
in a thin plate, which he calls the “equivalent orifice.” 

Fahrenheit. —The name of an eminent philosopher, born at 
Dantzic, who graduated the thermometer in the manner it is 
now used in England and America, and which is called by his 
name. By this scale the freezing point is placed 32 degrees 
above zero, and the boiling point at 213 degrees. (See Centi¬ 
grade and Reaumur), 


39 


Feeder .—Small stream or blower of gas. 

Fifth Power .—The result of a number multiplied five times 
into itself—thus 2 5 = 32 ; and the fifth root of 32 = 2 and is 

written thus sj 32=2. A knowledge of these numbers will be 
of use in calculations with respect to ventilation; for example, 
the sides of square airways will vary in proportion to the 5th 
root of their lengths, when the roads are subject to the .same 
pressure and are to pass the same quantities ; and the length of 
the diameters of circular airways will in the same way vary in 
the proportion of the fifth root of their lengths; and again the 
power necessary for passing the same quantity of air in 
square airways of different sizes is in inverse ratio to the 5th 
power of the sides of the squares, and in circular airways or 
shafts is according to the inverse ratio of the fifth power of the 
diameters. 

Final Velocity .—The speed at which the air passes out of the 
upcast shaft, or where there is a mechanical ventilator, the 
speed of the fan at the tips. 

Fire-boss .—A man whose duty it is to examine the working's 
for accumulations of explosive gas, etc. 

Fire-damp .—An explosive gaseous mixture. 

Fire-stink .—The name given in the South Staffordshire coal 
mines to the disagreeable smell arising from decomposed iron 
pyrites or the products of the spontaneous combustion of coal 
or other minerals. 

Friction .—Same as drag or resistance. 

Fugitive Air .—The air which escapes from the intake to the 
return, without passing through the mine, may be so called. In 
many cases a large quantity of air enters the mine by the down¬ 
cast, and escapes from the upcast, then passes around the work¬ 
ings. For example, at F, a mine in the Fifth Bituminous district 
of Pennsylvania, the mine inspector reports that the air ex¬ 
hausted by the fan is 24,000 cubic feet whilst the quantity in 
the workings is only 7,600 feet. It does not necessarily follow 
because there is not so much air in the workings as goes into 
and returns from the mine by the shaft that the difference is 
wasted : a part of the air which goes into the mine may very 
properly be allowed to leave the main current to pass through 
old or unused workings and make its way to the return with¬ 
out going into the working places; care, however, should be 
taken that no air is allowed to run away from the intake current 
unless it be required for the separate ventilation of some place 
isolated from the working places. Air after having passed 
through the gob should not pass through the workings, but go 
direct to the return. 

Furnace .—A large fire placed near the bottom of a shaft to 
reduce the density of the air and and cause a circulation. This 
appliance for producing ventilation, so well known to miners, 
is gradually falling into disuse, and therefore a detailed descrip¬ 
tion of it is unnecessary. 


40 


Goaf. —The abandoned part of a mine where the coal has been 
extracted. 

Gob. —The same as goaf. 

Gob-fire. —A fire which takes place in the gob or goaf, very 
often spontaneously, from the slack or fine coal left belli nil. 
(See par. 76, Chap. I.) 

Horse Power. —A term used in mechanical calculations 
meaning 33,000 lbs. lifted one foot high in a minute. If a weight 
of 660 lbs. be lifted 100 ft. high in a minute that represents two- 
horse power. The term is often used in calculations relating to 
ventilation; for example, if a fan delivers 99,000 cubic feet of air 
per minute with a pressure of 6 lbs. to the square foot, then the 
horse-power in the air would be eighteen, because 

99,000x6 
33,000 ~ 18 ' 

Hygrometer. —An instrument intended for gi ving precise meas¬ 
urements of the state of the air as regards moisture. Mason’s 
hygrometer has been recommended as better than others for 
ascertaining the proportion of moisture in the air of mines. It 
consists of two “ similar thermometers, mounted at a short dis¬ 
tance from each other, the bulb of one of them being covered 
with muslin, which is kept moist by means of a cotton wick 
leading from a vessel of water. The evaporation which takes 
place from the moistened bulb produces a depression of tem¬ 
perature, so that this thermometer reads lower than the other by 
an amount which increases with the dryness of the air.” Sat¬ 
urated air is lighter than dry air. For further particulars on 
this subject the student is recommended to consult any element¬ 
ary work on natural philosophy. 

Intake. —The road along which the fresh air passes into the 
mine is called the “intake,” and the current that flows along 
it is called the “ intake air.” 

Iron Pyrites. —This is a mineral substance frequently found 
in coal, and called by the miners of England “ brass” or 
“brazil.” It is sulphide of iron, and the chemists give it the 
symbol of Fe S 2 . When pyrites is present in coal heaps, its 
oxidation frequently gives rise to what is known as spontane¬ 
ous combustion, although such occurrences may take place 
without the presence of this substance. 

Lampman. —The man who attends to the cleaning, trimming 
and lighting of the safety-lamps. 

Lamp Station. —(Eng.) The place in the mine where the 
lamps are re-lit, in case of their having gone out, and to where 
they are to be taken if they require attending* to. The station 
should be placed in the intake air-current. 

Manometer .—Another name for water-gauge. 

Manometrical Effect. —Manometrical effect or manometric 
yield is the proportion which the actual water-gauge of a mine 
bears to the theoretical water-gauge. The actual water-gauge 



4i 


may be observed by taking the reading of the instrument in a 
fan drift. The theoretical water-gauge is calculated by the 
following rule: 


Let f = weight of a cubic foot of air in pounds. 
Let g = force of gravity = 32-2. 

Let v = velocity in feet of tips of fan per second. 
Let iv = water-gauge in inches ; then 


w =- 


T x/ 

5*2 


Marsh Gas. —Carbureted hydrogen or fire-damp, known like¬ 
wise by the names of methyl hydride and methane. The 
chemical symbol is CH 4 . 

Mephitic Gas. —Animal effluvise and exhalations, which be¬ 
come not only offensive but poisonous when a number of men 
or animals are huddled together in a limited space unprovided 
with ventilation. 

Motive Column. —A head of air, or the length of an air 
column, generally reckoned in feet, of the same density as the 
flowing air, equal to the pressure producing the ventilation. 

Mueseler. —The name of a safety-lamp invented byMueseler. 
Its construction is similar to the Clanny, but it is provided with 
a conical shaped chimney supported by a horizontal gauze on 
the top of the cylinder. It gives a pleasant light, and has 
proved to be safer in practice than either the Davy or Clanny. 
The illuminating power of this lamp is much greater than 
either the Clanny, Stephenson, or Davy. It is extensively used 
in the coal mines of the Continent and England. 

The bonneted Mueseler was one of the safety-lamps recom¬ 
mended by the members of the Royal Commission on Accidents 
in Mines, 1886. (Great Britain.) 

Natural Ventilation. —The air-current due only to the differ¬ 
ence in temperature between the outer air and that of the 
mine. In some small collieries this is sufficient for all purposes ; 
indeed in some large mines it is relied upon, and as an in¬ 
stance the writer may mention the case of Walsall Wood, in 
Staffordshire, a large and very deep mine. The downcast and 
upcast are both of the same diameter—if he believes rightty, 
about 16 feet—and the ventilation of the underground work¬ 
ings is carried on continuously without the aid of either a fan 
or furnace. It is not generally reliable, as the variation of 
the temperature sometimes causes the direction of the air-cur¬ 
rent to change, which we know by experience. 

Naked Light. —An open unprotected light, not provided 
with gauze or anything else. 

Old Man. —Same as gob or goaf. 

Perimeter. —The measure of the outline of a section of a 
figure ; thus, the perimeter of a road 4 ff. square would be 16 ; 



42 


the perimeter of a road 6 ft. by 5 ft. would be 6 + 5 -f- 6 — J- 5 — 
22. The perimeter of a circular shaft or tunnel 10 ft. diameter, 
would be 10 X 3-1416 = 81 416 ft. 

Pieler Lamp. —This may be described as a large Davy lamp, 
constructed to burn alcohol with an argand wick. The air sup¬ 
plied to the inner part of the flame is admitted by a tube, pro¬ 
tected by superposed discs of gauze, which passes vertically 
through the vessel containing the alcohol. Around the flame 
is a short, conical chimney, open above and below, and the 
flame is so regulated that it does not appear above the chim¬ 
ney, its height being, therefore, from 1 to 1-25 inches. In gas 
this spirit flame yields a much more conspicuous cap than can 
be produced by the flame of ordinary vegetable or animal oil. 
It is a sensitive gas detector, and in the form now used the 
flame is extinguished by the ignition of the gas. 

Piped An*.—Air passed through tubes or pipes to ventilate 
advance headings. 

Plenum. —“A mode of ventilating a mine or a heading by 
forcing fresh air into it.” (W. S. Gresley). 

Power of Ventilation. —The amount of force in operation to 
produce the current of air in circulation. It may be reckoned 
in units of work or horse-power, and is obtained by multiplying 
the pressure by the quantity. 

Pressure of Ventilation. —This is the motive-force obtained 
by rendering one end of an air-current of less density than the 
other, and the flow of the air will be in the direction of the 
rarefied air; this may be done either by heating the air or by 
exhaustion in the upcast. The difference of density between 
the intake and return is generally measured by the water- 
gauge. 

Propane. —A mixture of carbon and hydrogen, (C 3 H 8 .) A 
small proportion of this gas has been found in samples of the 
natural gas issuing from the Pennsylvania oil regions. 

Quantity. —When the ventilation of a mine is spoken of in 
England and America, it is generally said that the quantity 
passing is so many cubic feet per minute; on the Continent 
the quantity is reckoned in cubic metres. 

Reaumur. —A celebrated French naturalist, a member of the 
Academy of Sciences, B. 1683, D. 1757. He was the inventor 
of the thermometer which bears his name, by the scale of 
which, the freezing point is fixed at zero (0°) and the boiling- 
point at 80°. (See Thermometer, Centigrade, and Fahrenheit.) 

Reciprocal. —When the writer has used this word he intends 
it to signify the result of a number divided into one ; thus, the 
reciprocal of 2 = *5, of 4 = "25, and of 8 = -125, etc. One quan¬ 
tity is the reciprocal of another, when the one is the result of 
unity divided by the other. The product of a quantity by its 
reciprocal must always be unity. The student should remem¬ 
ber this mathematical expression, which is sometimes made 
use of in calculations referring to ventilation as in the state- 


ment : “ when the air-courses are of the same area and perim¬ 
eter, and the pressure is the same, the quantities are in pro¬ 
portion to the reciprocal of the square root of the length.” 

Regulator .—A stopping or door having a hole in it to allow a 
scale of air to pass through in just sufficient quantity for ven¬ 
tilating the district through which it has to pass. Air always 
takes the short cut, or the road where there is the least resist¬ 
ance ; hence, in short splits or roads to the return or the up¬ 
cast it is necessary to regulate the air passing in these short 
roads by allowing only the necessary quantity of air to pass 
through a scale or regulator. 

Resistance. —This means the same as the drag or friction of 
the air. 

Return. —This means the road or channel through which the 
air flows on to the upcast, after it has passed through the work¬ 
ings of the mine. Return air is the air which lias traveled 
through the mine. 

Rise-workings. —Openings in a mine which are above the 
bottom of the shaft or slope—to the rise—or up towards the 
crop. 

Rubbing-Surface. —The area of the roof, bottom and sides of 
the passage against which the air rubs as it flows along, and is 
generally expressed in square feet. For example, if an ab¬ 
road be 1000 yards long, 6 ft. high and 7 ft. wide, the rubbing- 
surface will be 78,000 square feet. 

Safety-Door .—A strongly constructed door kept in readiness 
should the main door or separation dcor be blown down by an 
explosion. The hinges are so made that the door can swing up 
against the roof, from which a sufficient space has been cut 
away, where it remains quite out of the way in ordinary times, 
but ready for use in case of accident. A door of this kind, called 
an “extra main-door,” according to the Anthracite Mine Law 
of Pennsylvania, shall be placed and kept standing open, out of 
the reach of accident so that it can be at once closed in the 
event of an accident to the doors in use. 

Safety-Lamp. —A lamp constructed for the safety of the 
miner, designed to prevent fire-damp from exploding. There 
are many varieties, some of which have been referred to under 
the headings of Davy, Stephenson, Mueseler, etc. 

Scale of Air .—A small portion of air allowed to pass from the 
main current to ventilate some isolated place. 

Sound Wave. —An undulatory movement of the air, which 
may be caused in a mine by the firing of a shot, or a fall of 
roof; in this way one mass of air is passed on to another. 
There is strong presumptive evidence that many explosions of 
gas have been occasioned by sound waves where the Davy 
lamp—the most dangerous of all safety-lamps—has been in 
use. 

Sjjlit. —A division of the air-current; a current of air sepa¬ 
rated from the maip air-current. To split the air is to send the 


44 


current along two or more roads instead of one. By dividing 
one current into two equal splits there will be two roads, eacli 
of half the length, but of the same area as the original air-way ; 
with three equal .splits there will be three roads, each one- 
tliird the length, but of the same area, as the original air-way, 
and so on ; at least that is the meaning intended by Atkinson 
in his treatise on the “ Friction of Air in Mines.” 

In practice, however, the conditions he calculates upon, do 
not exist in a mine. The calculations illustrate the advantages 
of splitting the air, so far as it can be done practically. When 
the same quantity of air is required in each split, it is well to 
have the passages of equal length and area, so that regulators 
may be avoided. See paragraphs 33 and 34, Chap. I. 

Square Root. —A number which, multiplied into itself, gives 
the square number ; thus, 3 is the square root of 9. 

Standing Gas. —A quantity of gas existing in an under¬ 
ground excavation through which no current of air is passing. 

Static Gauge.-— This word has recently been introduced into 
the literature of mine ventilation to signify the water-gauge 
placed in a recess of the main return air-drift a short distance 
to the windward of the fan. It is placed in this position so as 
to be away from the influence of the eddies of the air-current, 
and to give a true reading of the actual pressure producing the 
ventilation of the mine. 

Steam Jet. —An arrangement by which steam is allowed to 
escape at high pressure from a large number of small orifices, 
made in iron pipes, upwards into the upcast, thereby producing 
an air-current. This mode of producing” ventilation is not so 
efficient as the other methods. A comparison of the economy 
of four ways of ventilating is given in the Transactions of the 
Mining Institute of Scotland, Vol. 1, from which the following 


particulars are taken : 

Proportion of coal 

Mode of Ventilation. required for a given 

quantity of Air. 

Steam jet_ 1000 

Furnace__ 350 

Centrifugal open running fans_ 150 

Centrifugal fans on the Guibal Principle_ 120 


Stephenson. —The name given to the safety-lamp invented 
by the celebrated George Stephenson. It has proved to be in 
practice a safer lamp than the Davy, but it does not give so 
good a light. In the construction of this lamp there is an in¬ 
ternal glass cylinder with a perforated metal cap, surrounded 
by a cylindrical gauze. The air necessary for the combustion 
of the wick passes through perforations in the frame of the 
lamp, through the lower part of the gauze, and below the glass. 

Stone-damp.—See W hite-damp. 

Styihe. —A word used in the Northumberland and Durham 
coal Held, meaning choke-damp, or carbonic acid gas. This 






45 


gas is likewise called black-damp. The writer may say here 
that he has found in his experience—in the Five-quarter Seam, 
Blackboy Colliery, Durham—that a body of gas in a goaf or 
gob, will at one time give indications of black-damp, and at 
another time will indicate fire-damp; the change in the indi¬ 
cations is probably due to the altered conditions of the out¬ 
ward atmosphere as regards pressure and temperature. 

Sulphur.— A word frequently used amongst the South Staf¬ 
fordshire miners to signify carbureted hydrogen, and likewise 
formerly by the old miners of Durham. 

Thermometer.— An instrument for indicating variations in 
temperature. It generally consists of a slender glass tube, 
having a bulb at one end, and being sealed at the other. The 
bulb and a portion of the tube contain mercury, the rest of the 
tube being a vacuum. When the temperature is raised or low¬ 
ered, the mercury expands or contracts, so as to occupy a por¬ 
tion of the tube less or greater than before* and the amount of 
expansion or contraction is indicated by a scale attached to 
the instrument. The Fahrenheit scale is used generally in 
England and the United States of America, the Reaumur in 
France, anti the Centigrade in Germany. (See Fahrenheit, 
Centigrade, Reaumur.) 

Troughs. —A word used in Staffordshire, meaning the iron 
tubes used for passing air through. 

Units. —A mechanical expression meaning the pounds lifted 
one foot high in a minute. The pressure per square foot of the 
ventilation (in pounds) multiplied by the cubic feet of air pass¬ 
ing per minute will give the number of units ; 33,000 units = 
1 horse power. 

Upcast. —The shaft through which the return air of a mine 
ascends. 

Velocity. —The speed at which air travels, generally reckoned 
at so many feet per second or minute and is usually ascertain¬ 
ed by the revolutions of an anemometer. The speed multiplied 
by the area gives the quantity. 

Ventilate. —To pass fresh air by or through. 

Ventilating Fan. —A revolving machine placed at the top of 
the upcast for exhausting the air from a mine. As it revolves 
it maintains a partial vacuum at the top of the shaft, which the 
air of the mine comes in to fill, and so a current is created. 
The fans now in operation are of various kinds, known by the 
names of the inventors, such as Waddle, Guibal, Fabry, Lemi- 
elle, Nixon, Root, Struve, Capell, Rammell, Schiele, Chandler 
and others. 

Ventilator. —Same as ventilating fan. 

Waste. —Means generally in the North of England, the return 
part of a mine. In Cannock Chase district, the vacant space in 
the gob, along the face between two stall roads. 

Wasteman.—A man who looks after the ventilation or air 
roads. (Northumberland & Durham coal field.) 


Water-blast If by any means water should find its way into 
the bottom of a shaft, from which the workings are extended to 
the rise, and the water should ascend in the shaft, the water 
will not extend into the whole of the upper workings, on ac¬ 
count of the air there, which acts like a cushion as it becomes 
pressed into a smaller space as the water fills up the shaft. 
The pent-up air of the mine, and the water in the shaft will be 
in equilibrium. When the water comes to be pumped from the 
shaft, as it is lowered, the equilibrium will be destroyed, and 
eventually the compressed air will rush out with some force, 
causing a sudden rising of the water in the shaft. This phenom¬ 
enon is known as a water-blast which Mr. W. S. Gresley in 
his Glossary says is “ the sudden escape of pent-up air in rise 
ivorkings under considerable pressure from a head of water 
which has accumulated in the lower workings.” 

The following description of this phenomenon appeared in 
the Colliery Guardian of March 4th, 1892. 

Suppose a colliery with inclined measures to be abandoned 
or possibly having to be flooded to extinguish fire ; the air on 
the rise side of the shaft will be shut off from any exit and 
compressed by the water as it rises in the shaft and advances 
into the rise workings. When the water assumes a great 
height in the shaft, this compressing force is very great and 
the air, through its elasticity, reacts with the same force. If 
anything occurs to destroy this equality of forces, and the air 
gains preponderance, this will surely happen, if the mine has 
to be unwatered it will break its confinement and rush to the 
shaft in great volumes ; here, its elastic energy reacting* first, 
lifts the whole body of water in the shaft up; next freeing* 
itself from the water it suddenly assumes its normal volume 
and escapes from the shaft at a very high velocity, and the 
water subsides to a point far below its usual level. In brief, a 
drowned-out mine is the condition essential to a water-blast. 
The phenomena are a sudden uprising of the water in the shaft 
accompanied with considerable noise, a discharge of air prob¬ 
ably charged with gas at high velocity, and a sudden sub¬ 
sidence of the water in the shaft. 

Water-gauge .—An instrument formed of a glass tube in the 
shape of the letter U. When one end of it is passed through a 
small hole in a partition between the intake and return air, the 
difference of the height of the water in the two legs, is a meas¬ 
ure of the pressure of the ventilation. If the difference be one 
inch, the presure will be 5*2 lbs. per square foot; if two inches, 
10*4 lbs. 

Watery Vapor .—The moisture contained in the atmosphere. 
A given volume of air cannot take up more than a certain 
quantity of moisture at a given temperature, but when it takes 
up that quantity it is said then to be saturated with it. As the 
temperature of the air increases, it becomes capable of taking 
up more water. The average amount of water held in sus- 


47 


pension is about a pint in 2,500 cubic feet of air. The return 
air of coal mines is often saturated with watery vapor. 

Wliite-damp .—The name given by some miners to carbonic 
oxide : from what took place at the spring meeting, 1893, of 
the Illinois Mining Institute, it appears likewise to be called 
stone-damp. This gas is described in par. 70, Chap. I. ; we 
may, however, add here that it is composed in volume of one 
part of carbon and one of oxygen. It is highly explosive when 
two parts of it are mixed with five parts of air. Some of the 
explosions which have occurred in the mines of Staffordshire 
have been attributed to the presence of this gas—originating 
from gob-fires. 

It is found in mines, especially where gob-fires exist, and is 
produced by imperfect combustion. It is frequently met with 
in the mines of South Staffordshire, where gob-fires are very 
general. It is found in small quantities in the after damp of 
colliery explosions. It is present in considerable quantities in 
the after-damp formed in explosions where coal dust forms 
part of the combustible material. It is formed by the combus¬ 
tion of gunpowder, and in all cases where carbon is not suffi¬ 
ciently burnt for want of oxygen. 

It is to be seen over a still red fire in a furnace burning with 
a blue flame. 

It is generated spontaneously in a gob from the accumulation 
of slack left there. 

It has been found in a very small proportion, in some sam¬ 
ples of fire-damp in Germany, and in the natural gas of Penn¬ 
sylvania. 

"Excepting possibly in a very small degree, it is not likely to 
be present in a mine without combustion of some kind be going- 
on somewhere in the workings of the mine. 

Wind-cowl .—An iron tube made somewhat in the form of the 
trumpet like pipes which are to be seen on the decks of steam¬ 
ers for sending down a current of air into the cabins. This 
arrangement is used at the mines of Scotland and elsewhere 
for sending fresh air into a mine, but any current obtained by 
this means is very uncertain and irregular. This contrivance is 
to be seen at some of the shallow mines of South Staffordshire 
where it is called a horse's head. 

Wind-gauge .—An instrument for obtaining the speed at 
which air travels in a mine, the same as anemometer. 

Wind-way .—The same as air-way. 


48 


CHAPTER III. 

PRACTICAL NOTES ON COAL DUST AND COLLIERY EXPLOSIONS. 

Any treatise on the subject of mine ventilation and colliery 
explosions must necessarily be incomplete without some refer¬ 
ence to the question of coal dust. 

The subject is one of great importance, considering the large 
number of lives which are lost from colliery explosions. The 
following statement shows the loss of life in Great Britain from 
this cause : 


Years. 

Average 
number of 
lives lost 
per 

annum. 

One life lost 
to number of 
persons 
employed. 

Ten years to 1860 _ 

244 

1008 

Ten years to 1870_ 

226 

1414 

Ten years to 1880____ 

269 

1795 

Ten years to 1890 ___ 

166 

3199 

Year 1891 ..._ 

51 

12714 

Year 1892 __ 

123 

5400 


Recent reports of the inspectors of mines, in the different 
States, have drawn attention to the serious effect coal dust has 
on explosions, especially in extending them. The inspector for 
the Second Bituminous district of Pennsylvania, in his report 
for 1891, recommended the coal dust of dry mines to be damp¬ 
ened. In the anthracite coal mines of Pennsylvania, in 1891, 
the number of lives lost by explosions was 38, and in the bi¬ 
tuminous mines, 111. 

It has long been known that the presence of coal dust in very 
dee]) mines, in the case of an explosion of fire-damp, very much 
intensifies the force and extent of the explosion. 

During the last few years it has been repeatedly asserted by 
some of the British inspectors of mines, that an explosion will 
occur from coal dust in itself, without the presence of fire¬ 
damp. 

One of the principal objects the writer has in view in making 
these remarks is to induce the coal miners, as well as the mine 
officials, to take an interest in the question, and consider it for 
themselves. 

Dr. Lyon Playfair and Professor Faraday, in reporting, in the 
year 1845, on the Haswell Colliery explosion, County of Dur¬ 
ham, which occurred the year previously, stated that they had 




















49 


found the clothes of the miners scorched and crusted over more 
or less with coke and ash, owing to the presence of coal dust. 
Sir Frederick Abel, in publishing the results of his investiga¬ 
tions into an explosion at Seaham Colliery, stated that dust 
which contained very little coal was often able to produce 
almost as much effect in causing the tire, as dust which was 
almost purely coal. That was confirmed by the fact that lie 
could produce the same results by mixing gas and air with fine 
slate dust, clay dust, powdered pumice, and even powdered 
magnesia—all powders which no one would imagine would 
burn in themselves. From this it is concluded that all dust, 
not only the dust of pure coal, is more or less dangerous. 

The reports of the British inspectors of mines for recent 
years contain several references to the part played by coal dust 
in explosions, and as they bear so closely to the subject under 
consideration, the writer considers it advisable that he should 
draw attention to some of them. On April 24, 1889, an explo¬ 
sion occurred at Brancepeth Colliery, Durham, from the light 
of an open torch lamp used by the workmen in cleaning out 
the fine dust from the hoppers, by which three men lost their 
lives. The verdict returned at the inquest was “ Death caused 
by the firing of coal dust coming in contact with naked lights,” 
with the recommendation that no naked lights be taken into 
the coal hoppers in the future. 

In his report on the Mossfields Colliery explosion, which 
occured on October 16th, 1889, the mine inspector says: “This 
disaster is another example of how an explosion is extended by 
coal dust, and the loss of life greatly increased in consequence. 
The normal condition of a dry and dusty colliery, or of a colliery 
in which the roads connecting* different districts are dusty, is 
such that a terrible explosion is possible at any moment.” On 
November 4th, 1889, an explosion occurred at Hebburn Colliery, 
of which the inspector said he did not feel justified in calling it 
entirely an explosion of fire-damp. The hole was charged with 
gelignite and roburite together, and in the opinion of the in¬ 
spector, the explosion was caused by the flame being blown out 
from this fast shot, assisted by any small quantity of fire¬ 
damp that might be present. Another example of coal dust 
exploding without the presence of fire-damp took place in 1890 
on the pit-bank at one of the collieries in the Yorkshire district, 
particulars of which are given by the inspector in his annual 
report. Some very fine coal dust had accumulated on a plank; 
in turning over the plank, which it was necessary to move in 
making some repairs to an engine, the dust fell upon torch¬ 
lights and an explosion occurred and burnt several of the men 
very seriously. Coal dust is exceedingly dangerous when 
mixed with a small quantity of fire-damp, 4 per cent, of gas 
mixed with air will not explode, but it will when line coal dust 
is mixed with it. In 1890, Mr. Henry Hall, one of the inspect¬ 
ors of mines in Grecit Britain, made certain experiments in 


50 


three different shafts to ascertain if coal dust by itself is explo¬ 
sive. The way he proceeded was to sprinkle fine dust ia. the 
shaft and fire off a cannon pointed upwards, placed at the bot¬ 
tom of the shaft in each case. In several cases the dust was 
ignited, and the flame ascended the shaft and rushed out of its 
mouth at the top to a height of from 20 to 40 feet. From these 
experiments he concludes that they “prove that blasting with 
gunpowder in dry and dusty mines may cause serious disasters 
in the entire absence of fire-damp.” With respect to these ex¬ 
periments it may be remarked that the action of a flame 
amongst coal dust must necessarily be very different in a hori¬ 
zontal gallery to what it would be in a vertical shaft; for the 
tendency of flame is to rise, the same “ as the sparks fly up¬ 
ward,” and it may be doubted whether such a result would be 
obtained in firing a cannon along the level road of a mine as 
that in a vertical shaft. 

Further experiments of a similar kind, though under some¬ 
what altered conditions, were made by the same inspector in a 
Lancashire pit, England, at the end of 1892, and beginning of 
1893, which have confirmed his opinion that explosions will 
occur from coal dust by blown out shots without the presence 
of fire-damp. 

The experiments were made by firing off a cannon, with a 
charge of about 1^ lbs. of gunpowder, into a shaft in which a 
quantity of fine coal dust was floating, or which was deposited 
on the timber in the shaft, which was wet; the shaft was 50 
yards deep and 7 feet diameter, having pieces of limber fixed 
across every 6 or 7 feet at the side to represent timbering un¬ 
derground, and to afford a lodgment for the dust. 

The experiments were made with and without the working 
of a small hand fan which, when operated, blew the air down 
10-incli pipes to the bottom of the shaft. 

From these experiments Mr. Hall deduced the conclusions 
that: 

1. Dry coal dust, under conditions frequently present in coal 
mines, and in the entire absence of fire-damp, may be inflamed 
by a blown out gunpowder shot and cause a disastrous colliery 
explosion. 

2. An explosion will occur when there is actually no coal 
dust in suspension, but when it is lodged on the timbers or on 
the sides. 

3. A gunpowder shot will explode coal dust, whilst blasting 
with roburite will not do so. 

4. Any colliery in which the seams are naturally of a dry and 
dusty character cannot be successfully damped so as to render 
gunpowder safe. 

5. With the increased ventilation produced by the operation of 
the fan the experiments were more decisive, showing that the 
brisker the ventilation of a mine the greater the danger from 
cogl dust, 


51 


Explosions have occurred from small particles of other sub¬ 
stances besides coal, such as Hour, cotton flue, rice dust and 
sawdust. In June, 181)2, an explosion of malt dust occurred in 
one of the top stories of Bell’s Brewery, Stafford, by which the 
roof was blown off and considerable damage done, and numer¬ 
ous instances are on record of explosions of flour dust taking 
place in flour mills. 

An explosion of this sort took place on March 24th, 1893, at 
the Keeler Flouring Mill, Litchfield, Ill., when the immense 
structure was blown to fragments. 

There is a considerable difference in the chemical composi¬ 
tion and mechanical structure of various samples of coal dust; 
there is a difference in the chemical composition of the dust of 
the same coal, brought about by time; new coal dust and old 
coal dust have very different compositions, because the oxygen 
in the air will remove some of the constituents. 

The writer possesses the settled conviction that the dust of 
the coal mines of many coal fields is inexplosive ; this opinion 
is forced upon him from the fact of the immunity of these 
mines from explosions of dust during the whole period of their 
history. Various examples may be mentioned—one will be 
given in the absence of any special experiments being made to 
test the question, but after fourteen years’ observation, it is the 
opinion of the writer and many mining engineers of the Can¬ 
nock Chase district, Staffordshire, England, that the dust in 
the underground workings of the collieries there will not ex¬ 
plode of itself, nor will it intensify or extend an explosion of 
fire-damp. Neither collier or manager can see any danger from 
coal dust in these mines ; the dust is more of an argillaceous 
than carbonaceous character. It must be borne in mind how¬ 
ever, that Sir Frederick Abel, in speaking of certain dust of the 
Seaham Colliery, says it may be a source of danger even 
though it contains only a small proportion of coal or combusti¬ 
ble matter ; in fact, Sir Frederick ascertained that a dust which 
would not itself burn could possibly aid in making a mixture of 
gas and air explosive. Fire-damp, as it escapes from the coal 
in a mine, is not explosive ; it requires to be mixed with air in 
certain proportions before it will ignite. With a mixture of 
one of gas and twenty of air there will be no explosion. 

Some mining engineers have questioned the statement that 
it is possible in a shot hole, where gases are given out b} T 
feeders, that firing a shot will ignite the feeder. The writer, in 
his own experience, can mention one case, at least, where the 
firing of a shot by gunpowder set fire to a feeder of gas ; the 
gas continued to burn a considerable time afterwards, with a 
flame several feet long. This occurred in driving a tunnel from 
the Catherine seam to the Gustavus seam, at Hansa Colliery in 
Westphalia. There are many other similar occurrences on 
record. It has been argued that a feeder of gas at the back of 
a hole could obtain no atmospheric air—there would be an 


52 


absence of oxygen—and without that element the gas could 
not he ignited. It is true that if a flame be introduced into gas 
there would be no ignition without air ; but the composition of 
the gases given off from coal or the associated rocks varies 
very much, and in firing a shot, the necessary oxygen might 
get access to occasion explosion. 

About two years ago a Commission was appointed in Eng¬ 
land, of which the Right Honorable Joseph Chamberlain is 
Chairman, to enquire into the dangers of coal dust in mines, 
before which numerous witnesses have been examined, includ¬ 
ing both mining and scientific experts. The labors of this 
Commission are not yet ended, but we believe will shortly be 
brought to a close, after which will come the publication of 
their report. 

No coal dust explosion has taken place in the actual experi¬ 
ence of the writer in any of the mining districts in which he 
has been engaged during his career. 


CHAPTER IV. 

RULES AND FORMULA APPLICABLE TO VARIOUS QUESTIONS RE¬ 
LATING TO THE VENTILATION OF MINES, THE PRESSURE AND 
TEMPERATURE OF THE ATMOSPHERE, AND TO THE CIRCULA¬ 
TION OF AIR IN PASSAGES, ETC. 

The subject of mine ventilation is one that ought to be stud¬ 
ied by every intelligent miner, as well as colliery official, for the 
safety of a mine, especially as regards ventilation, depends not 
only upon the competency of the mine officials, but upon the 
action of every indivdual in the mine whatever his position 
may be. In studying the subject the miner should be able to 
attack it from any position. With this in view the writer lias 
brought together a number of rules and formulae applicable to 
the subject under various conditions and circumstances. Some 
of the formulae have appeared elsewhere and have almost be¬ 
come the common property of engineers generally; many of 
them are quite new, others are presented in a new form, and 
all have been arranged with a view of being practically useful. 
Although the rules might be elaborated and extended, the writer 
believes sufficient are given to enable the student to consider 
the subject in the various aspects in which it may be presented, 
and to work out most of the questions that may be met with 
in practice. 

Many other rules relating to the co-efficient of friction might 
be given under VII. ; indeed, more will be found in the table of 
co-efficients, which will appear in the next chapter. With re¬ 
gard to the co efficient of friction, the writer must maintain that 



53 


his co-efficient of *00000001 lbs.* per square foot for a velocity 
of one foot per minute, which he has always recommended, is 
sufficient as an average for the air passages of coal mines, and 
he has worked out numerous examples accordingly, as will be 
seen in these papers further on. Murgue, in experiments on 
the subject, which he has recently published, makes it less even 
than the writer puts it at. It must be remembered, however, 
that it varies with the nature of the sides of the channels, that 
it increases in roads of small section as the area diminishes,— 
that, in fact, it is a variable factor. 


I. The following rules apply to the friction of air in moving 
along* passages and underground roads: Let a = area of air¬ 
ways in square feet; li = horse power of ventilation ; k = co¬ 
efficient of friction ; Z = length of air-channel; o = perimeter of 
air-channel; p = pressure in pounds per square foot; q = 
quantity of air circulating, in cubic feet per minute ; s = area in 
square feet of rubbing surface exposed to the air; u = units of 
work, foot pounds, or power applied to circulate the air ; v = 
the velocity of the air in feet per minute; w = water-gauge in 
inches; then 

1 ' _ & s‘ v 2 _ p a _ k s v* q _ k s v 3 _ u _ q _ 

p ~ p ~ u ~ p v ~ P v ~ v 

(1 



2 h - u - JUL~ 
33,000 33,000 


qw 5-2 
33,000 


3 ; fc = ?L_“ = JL 

S V s 


V 


p a 
k v ~o 


6. p — 

k s v 3 u 


S V s 

s 
o 

s __ p ft 

T ~ kv*l 
k s v 3 _ u 
a ~ q 


4 . 1 = — = ^ 


5. O — —r- = 


S V 8 -T- a 


W 5 5 

« v~ - 4 - a 


= 51 w 


■ Wfi 


ks 

a 


p a 
a 



* The co-efficient generally used is that of J. J. Atkinson,— 00()0(XX)217. The 
writer has found from numerous observations of the flow of air in shafts and 
mines, that this is far too high and that -00000001 is a more correct factor for most- 
cases. Murgue in his recently published paper on the subject makes it less even 
than this (See Colliery Engineer, August, 1893, p. 16). If it be required to 
ascertain the result, from a higher or a lower co efficient, it may be done by direct 
proportion;—for example, if the writer’s co-efficient gives a pressure of lib., 
Atkinson’s will give 2 - l?lb. Particulars of a large number of co efficients are 
given in Table 1 of next chapter. 







54 


n 

v 


7. p a = k s v~ — 
p a 3 — k .s- q 2 . 




h 33,000 
7r 5 2 



10 . n = qp 


k s v 2 q , . 

v p a — -- k s v a = q 5 J id — 


/t 33,000. 



13 r3 = jl _ = 


A; s k s k s 



II. To ascertain the motive column or the head of air due to 
difference of temperature, etc. 

Let M — motive column. 

Let T = temperature of upcast. 

Let / = weight of one cubic foot of the flowing air. 

Let t — temperature of downcast. 

Let D = depth of downcast. 

Then, 



P = / X M. 



III. Rule to find diameter of a round air-way to pass the same 
amount of air as a square air-way, the length and power re¬ 
maining the same. 

Let D = diameter of round air-way. 

Let A = area of square air-way. 

Let O = perimeter of square air-way. 

Then, 


D = 




A 3 X 3-1416 
•7854 s X O ' 







55 


IV. Rule to find the relative pressure or powers (R p) required 
to pass equal quantities of air through air-courses of the same 
length, but of different areas and perimeters. 



V. Rule to find the relative quantities (Rq) that will pass air¬ 
ways subject to the same pressure, but of different dimen¬ 


sions. 



VI. Rule to reduce a continuous undivided road of various 
dimensions, to one typical road of uniform size throughout : 


a' = area of typical road, o' = perimeter of same. 
s and a = rubbing surface and area respectively of the original 
uneven road at each series of dimensions. 

VII. Rule to convert the French (F) co-efficient of friction, or 
head of air, to the English (E) co-efficient, that is to say, the 
water-gauge in millimeters for each square meter of rubbing 
surface and a velocity of one meter per second, to the pressure 
per square foot in decimals of a pound for each square foot of 
rubbing surface, and a velocity of one foot per minute : 


F X *0393708 X 5*2 
10*76458 X 60 3 


When iv = ’00000001 lb. per square foot of rubbing surface 
for a velocity of 1 foot per minute, then 



VIII. To lind the quantity of air with a given horse power (h) 
and efficiency (e) of engine : 

_ h X 33,000 X e 
q ~ p~ 

IX. To find the weight (W) of a cubic foot of air at any tem¬ 
perature or height of the barometer : 


B = height of barometer in inches. 
t = temperature F. 


_ 1*3253 X B 
459 + t ' 







5G 


X. Formulae for converting the different thermometer scales 
into each other. F, C, and R represent Fahrenheit, Centigrade 
and Reaumur respectively : 


F = 32 + -|-C = 32 + -|-R. 
C = ~(F-32) = ^ R. 

R = 4-( f - 82 >='F c - 


XI. Rule to measure the air in a mine by gunpowder. 

Select an even part of the road from 50 to 100 feet in length ; 

ascertain its cubical contents in feet, let off a flash of gun¬ 
powder at one end of the road, and observe how long the smoke 
is in passing to the other end, then as the time in seconds in 
passing is to the cubic area, so is 60 seconds to the number of 
cubic feet passing per minute. 

XII. Formulae relating to equivalent orifice : 

Let Q = quantity of air in thousands of cubic feet per minute. 
w = inches of water-gauge. 

A = area in square feet of equivalent orifice, then, 


0*37 Q Q 
\/ w 2’7 |/ w 


Q _ A X 4 / w 


0*37 



XIII. Rules and formulae relating to the theoretical depres¬ 
sion, or pressure of air due to final velocity : 

Murgue says : The theoretical depression or water-gauge, due 
to the speed of the periphery is, in a perfect ventilating* fan, 
equal to twice the height of column of air necessary to generate 
such velocity in a falling body. From this proposition we give 
the following rules : 

Let v = velocity in feet of tips of fan per second. 

Let g = force of gravity = 32*2. 

LetM = pressure in feet of air or motive column. 

Let w = pressure in inches of water-gauge. 

Let / = weight of a cubic foot of the flowing air in Tbs.; then, 





57 


v = 8-025 



The factor 68, in these rules has been obtained by reckoning- 
water 816 times heavier than air, which, although it varies 
with the temperature, is the ratio at a temperature of 62° F.; 
so that to get the pressure expressed from head of air in feet 


816 

into inches of water-gauge, we have = 68. The factor for 

1-V 

5*2 d 

other temperatures would be more correctly or, divided 

J a 


by 12, d being the density of water, and d' the density of air at 
the same temperature. 


XIY. If two fans are employed to ventilate a mine, each of 
which when worked separately produces a certain quantity, 
which may be indicated by A and B, then the quantity of air 
that will pass when the two fans are worked together will 

be VA^+ B 3 - 


CHAPTER V. 

USEFUL TABLES RELATING TO MINE VENTILATION, AIR AND GASES. 

The tables annexed, the greater number of which are entirely 
original, have been prepared by the writer to facilitate calcula¬ 
tions relating to the motion, pressure, and expansion of air 
and other matters connected with the ventilation of mines. 

I. Table of the co-efficient of friction in the flow of air, 
through passages with different kinds of surface according to 
the undermentioned authorities, expressed in different terms 
agreeable to the measures used in the United States, Great 
Britain, France and Germany. 




ft <D 

2 w g 
O 5 * C -* 
ft ^ 

*-> <—« 
2 x >>-5 

o ft p 
C 

®flo- 

. *f—< fl) 

' 4 -^ 1 a; c, 

cc ^ ^-*e 
0/T 03O 

£ft w<2 
r ° o fl 
U« p 


O 

pi£ 

G p 

Sf g 

cc <— 

***■ 

‘r* w ^ 
a> o'— 
P**d 03 

9 g^ 

h* *pH O 

S 3 4^ 

CO ft 

* 2 
o O 
tnft 

Ph 


C 4 

o 

o 

o 


X 

P 


C 4 

O 

o 

o 


X 

ao 

Of 

o 

X 


X 

<J 


i- 

T—< 

Of 


o 

o 

o 

o 


or to 

r-H GO 

'X) iO 
X X 



o* 

tl 

<x 

y—> 

o 

O' 


o 

r—1 

o 

o 

o 

o 


o o 


tl 
r —1 

o 

o 


o 

o 


10 

CO 

a 

ft 

O 

Q 

o 

o 

o 

o 


ft 

o 

ft -4-J 

So 

P o 


OJ T 3 
• Cl 

s-. rz ~ 

~ *- o o 

Kf 2 o a; 

oDs . cc 
c p >»^ 

?- o*— o:£ 2 

o *3»o o o o, 

g — 03 0 4 * 
G S'Hp- O 
o* *■< a*> q 

CO >ft 




g 

P 

bX 


cc 

a 


o 

0 ) a 

4 - -r- 

n 




o* 

o 


r K 


ft co o 



i-WO-OOW 
CO ft O* 5 C ft 05 CO 

i-xoi-cao 1- 
05 iO ft X 10 iO »C 
10 O rH o 10 W rl 
p O © © ft © © 

ooloooo 


Oi 

O 

0 

05 

■ft 

g 

ft 

50 

CO 

50 

CO 

10 

05 

or 

O 


cc 

CO 

o* 

W* 

O 

X 

0 

y—i 

■ft 

50 

o* 

ft 

1 - 

§ 


O 


CO 

iO 



0 

0 

0 

0 


o 

o 


o 

o 


t- 

o 


*H O'O 

o .» a 0 

« 3 P O O 
aC'Oft £ 

ua°% 

a c 3 >j ^ 

Sc3 ft 

26 08 0-2 
G O^T! 0 
2 O 

CC k" ft 


cj 2 

C3 O 
O ft 


a? 


4 _J CC 

g p 

O ft 


rn •«—< 

^ p p 0 CC 

o 05 ^ 

<T 0 

ft - 1 


C-C 

cc*~ 


X 

O* 

?1 

o 

© 


X 

P 


P 


?- 
T—I 

Oi 

Tft 

X 

i- 

o 


ONlOO 
OWON 
iCrrOO 
10 O Ow 
O O? rft o 
O^ CO CO CO 

0000 

O' O O O 

0000 

0000 


OiCOO^W 

x*oiox 905 

COOiOO*Oi- 
CJ CO CO ft 
^NftOCOX 

OOOOOO 

000000 

OOOOOO 

OOOOOO 


0 

O* 

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X 

0 

Of 

X 

05 

O 

ft 

ft 

ft 

CO 

X 

O 



N 


J> 

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CC 


50 

50 

50 

a 

05 

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CO 

0 

ft 




O o 


o 

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o 


<ft 

c 


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o o 
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C "d 

eg 2 ® 

w o o 


t- 

p 

CO tH O 

g£ls?i 

r 5 - 0+ 3 

^ ft o 

cr t- 2 o 

CO >■ «H 


c° 

S • 

2 rt o 
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c-l 

o 

to 

X 

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■ " * O O o 
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2o3« ,X 
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s Pi£ft 

2 ft 

a)<M ft ss 

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$!•§;: 

£ 

cc.^ C 


X 

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L— 

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ftXftiOftcooft^o? 
ft 4 Oi ft 4 X Tft1 fti 50 Of 05 i" 
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cc cc x x 05 or ft Of co or 
O O O O O O ft-* 0* O' o 
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10 

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• _ i£ 4* 
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0" = O 

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ft' ft ft 
t- (ft *ft ^ 

Poop 

O o 


PQ 


X 
or 
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X i- O CO COX ft N l- l- ft 

X ft O to 50 i."* 50 50 C- lO X 

50 O ft O O ft Of 1— i — Tf 1 Of 

Of ftftriftftOftCiO O 


ft 

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s 

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-V.) 

II. Table showing* the pressure per square foot in pounds duo 
to the flow of air at different velocities in roads of different 
dimensions, as stated below, for a length of one mile, reckoning* 
the co-efficient at *00000001 lb. per square foot for a velocity of 
of one foot per minute. 


Size of 
square road. 

Diameter of 
round road. 

Velocity one 
foot per second. 

Velocity 
five feet per 
second. 

Velocity 
ten feet per 
second. 

ft. ft. 

ft. 

n,„ 

lbs. 

lbs. 

1 x 1 

1 

*7603 

19-00 

76-03 

2 x 2 

/V A fj 

2 

*3801 

9-50 

38-01 

3 x 3 

3 

*2534 

6-33 

25-34 

4x4 

4 

•1900 

4*75 

19*00 

5 x 5 

5 

•1520 

3-80 

15-20 

0 x 0 

6 

•1267 

3-16 

12-67 

7x7 

i 

•1086 

2-71 

10*86 

8x8 

8 

•0954 

2-38 

9-54 

0 x 9 

9 

•0844 

2*11 

8-44 

10 x 10 

10 

•0760 

1-90 

7-60 

11 x 11 

‘ 11 

•0691 

1-72 

6-91 

12 x 12 

12 

•0633 

1 *58 

6-33 

13 x 13 

13 

•0584 

1 -46 

5*84 

14 x 14 

14 

•0543 

1-35 

5-43 


III. Table showing* the quantity of air that will flow through 
a passage one foot area, at different velocities, and the pressure 
due to a length of one mile, reckoning* the co-efficient of fric¬ 
tion at *00000001 lb. per square foot for a velocity of one foot 
per minute. 


Velocity in feet 
per second. 

Cubic feet per 
minute. 

1 

Pressure per square 
foot in lbs. 

1 

60 

•76 

2 

120 

3-04 

3 

180 

6-84 

4 

240 

12-16 

5 

300 

19*00 

6 

360 

27-36 

7 

420 

37-24 

8 

480 

48-64 

9 

540 

61 -56 

10 

600 

76-03 



























60 


IV. Table showing length of roads offering resistance equal 
to one inch of water-gauge, of the dimensions below mentioned. 

k = -00000001 lb. per sq. ft. foi* a velocity of one foot per 
minute. 

v = 5 ft. per second = 300 feet per minute. 

m 

Rule, — = l in feet. 
k v 2 o 


Square Roads. 



Round Roads. 

Length of 

Dimensions 
of Road. 

a 

i 

o 

Dia. of 
Road. 

Area. 

Circumfer¬ 
ence or o. 

road 

in yards. 

ft. ft, 

1 x 1 

1 

4 

1 

•7854 

1 

3-1410 

481 

2x2 

4 

8 

2 

3-141 

0-2832 

962 

3 x 3 

9 

12 

3 

7-008 

9-4248 

1444 

4x4 

10 

10 

4 

12-500 

12-5004 

1926 

5 x 5 

25 

20 

5 

19 035 

15-7080 

2407 

0 x 0 

30 

24 

0 

28-274 

18-8490 

2888 

7 x 7 

49 

28 

rr 

i 

38-484 

21-9912 

3370 

8 x 8 

04 

32 

8 

50-265 

251328 

3850 

9x 9 

81 

30 

9 

03-017 

28-2744 

4333 

10 x 10 

100 

40 

10 

78-540 

31-4100 

4814 

11 x 11 

121 

44 

11 

95-033 

34-5570 

5290 

12 x 12 

144 

48 

12 

113-097 

37-0992 

5777 

13 x 13 

109 

52 

13 

132-732 

40-8408 

0259 

14 x 14 

190 

50 

14 

153-938 

43-9820 

0741 


























6i 


V. Table showing the water-gauge due to 30,000 cubic feet of 
of air passing through mines with the following equivalent 
orifices. 

Rule, w = 0T369 x ~ 

Q = quantity in thousands of cubic feet per minute. 


Equivalent 
orifice in 
square feet. 

Water-gauge 
in inches. 

Equivalent 
orifice in 
square feet. 

Water-gauge 
in inches. 

3 

13-69 

15 

•548 

4 

7-698 

16 

•481 

5 

4-928 

17 

•425 

G 

3-422 

18 

•379 

ty 

i 

2-513 

19 

• -341 

8 

1-925 

20 

•308 

9 

1-521 

21 

•280 

10 

1-232 

22 

•254 

11 

1-018 

23 

•233 

12 

•856 

24 

•214 

13 

•728 

25 

T97 

14 

•627 

26 

•182 


VI. Table of the values of the theoretical depression ex¬ 
pressed in inches of water-gauge and head of air in feet.—(See 
Rules and Formulae XIII., Chap. IV.) 


Speed in feet of 
the periphery 
per second. 

Depression in feet 
of air column. 

Depression in 
inches of 
water-guage. 

Speed in feet of 
the periphery 
per second. 

Depression in feet 
of air column. 

Depression in 
inches of 
water-gauge. 

V 

M 

W 

V 

M 

W 


v 2 

M 


v 2 

M 


32-2 

68 


3^2 

68 

30 

27-95 

0-411 

75 

174-69 

2-569 

35 

38*04 

0-559 

80 

198-75 

2-922 

40 

49-69 

0-731 

85 

224-38 

3-299 

45 

62-82 

0-924 

90 

251-55 

3-699 

50 

77 63 

1-141 

95 

280-28 

4-122 

55 

93-94 

1-381 

100 

310-55 

4-567 

60 

111-80 

1-644 

105 

342-39 

5 035 

65 

13M8 

1-929 

110 

375-77 

5-526 

70 

152-17 

2-238 

115 

410-71 

6-039 





































62 


VII. Table of the Elementary and Compound Gases, with 
their properties. 



— 




>» 





-4-5 

& 





'53 

M 

CSr-i 




£ <?i 

’3 

r»5 ii 

No. 

Name of Gas. 

o 

^ li 


II 

o 




« ^ 





B 

w 

Q 

C 

i 



. w. 



CO 

1 

Hydrogen_ _ . . 

H 

2 

1 

•06926 

2 

Light carbureted hydro -) 






gen, marsh gas or methyl j- 

ch 4 

16 

8 

•5592 

3 

hydride.. . . . ) 

Ammonia . . 

N H 3 

17 

8-505 

*586 

4 

Watery vapor or water gas _ 

h 3 o 

C 

18 

9 

•6235 

5 

Carbon_ _ _ 

24 

12 

•832 

6 

Carbonic oxide or carbon ) 
monoxide __ 

C 0 

28 

14 

•9678 

ry 

i 

Nitrogen _ _ 

N 

28 

14 

•9713 

8 

Heavy carbureted hydro- ) 


gen, or olefiant gas, or >• 
ethylene _ ) 

c 8 h 4 

28 

14 

•9784 

9 

Air . ... 




1 - . 

10 

Nitric oxide _ 

N 0 

60 

15 

1-039 

11 

Oxvsren __ _ 

0 

32 

16 

1*1056 


12 

Sulphureted hvdroeren_ 

H 0 S 

34 

17 

1-1748 



13 

Nitrous oxide_ ._ 

Nl O 

44 

22 

1*527 

14 

Carbonic acid or carbon ) 
dioxide ..... ) 

C 0 2 

44 

22 

1-529 

15 

Sulphur_ 

s 

64 

32 

1-95 

16 

Sulphurous acid ... 

s 0 2 

64 

32 

2-247 


































VIII. Table of the weight of a cubic foot of air, in decimals 
of a pound avoirdupois, at different temperatures, calculated 
from the rule, 

1-3253x30. 

W ~ 459 -f t 


Tempera¬ 
ture t. 

Weight in decimals 
of a lb. 

Tempera¬ 
ture t. 

Weight in decimals 
of a lb. 

32 

•0809749 

120 

•0686678 

35 

•0804831 

125 

•0680799 

40 

•0796767 

130 

•0675020 

45 

•0788863 

135 

•0669338 

50 

•0781113 

140 

•0663751 

55 

•0773515 

145 

•0658256 

r,o 

•0766063 

150 

•0652852 

62 

•0763122 

155 

•0647535 

65 

•0758753 

160 

•0642305 

70 

•0751582 

165 

•0637158 

75 

•0744544 

170 

•0632093 

80 

•0737638 

175 

•0627108 

85 

•0730858 

180 

•0622201 

90 

•0724202 

185 

•0617371 

95 

•0717666 

190 

•0612614 

100 

•0711246 

195 

•0607931 

105 

•0704941 

200 

•0603318 

110 

•0698746 

205 

•0598775 

115 

•0692660 

212 

•0592529 















of 


IX. Table showing the comparative composit ion of Lignite, 
Bituminous Coal and Anthracite. 



Lignite. 

» 

Bituminous 

Coal. 

Anthracite. 

Carbon_ 

Per Cent. 
66-32 

Per Cent. 

78-57 

Per Cent. 

90-39 

Hydrogen_ . _ 

5-63 

5-29 

3-28 

Nitrogen _ 

0-56 

1-84 

0-83 

Oxygen - 

22-86 

12-88 

2-98 

Sulphur___ 

2-36 

0-39 

0-91 

Ash_ 

2-27 

1-03 

1-61 

Total... 

100 

100 

100 

Weight of a cubic foot in lbs_ 

70 

80 

90 


As a comparison the following percentages may be taken as 
representing the average chemical composition of wood and 
peat. 



Ligneous 

Fibre. 

Peat. 

Carbon... _ 

50 

59 

Hydrogen__ 

6 

6 

Oxygen-- 

43 

33 

Nitrogen_ 

1 

2 

Total__... 

100 

100 














































65 


X. Table to show the Square Root erf Water-gauge Readings 
and Pressures. 


Water-gauge 
in inches. 

Square root of 
Water-gauge. 

Pressure in 
lbs. per sq. ft. 

Water-gauge 
in inches. 

Square root of 

Water-gauge. 

Pressure in 

lbs. per sq. ft. 

Water-gauge 

in inches. 

Square root of 

Water-gauge. 

Pressure in 

lbs. per sq. ft. 

•25 

•50 

1-30 

2-25 

1-500 

11-70 

4-25 

2-061 

22-10 

•30 

•548 

1-56 

2-30 

1-516 

11-96 

4-30 

2-073 

22-36 

•35 

•592 

1-82 

2-35 

1-532 

12.22 

4-35 

2-085 

22-62 

•40 

•611 

2-08 

2-40 

1-549 

12-48 

4-40 

2-097 

22-88 

•45 

•678 

2-34 

2-45 

1-565 

12-74 

4-45 

2-109 

23-14 

•50 

•707 

2-60 

2-50 

1-581 

13-00 

4-50 

2-121 

23-40 

•55 

•741 

2-86 

2-55 

1-596 

13-26 

4-55 

2T33 

23-66 

•CO 

•774 

3-12 

260 

1-612 

13-52 

4-60 

2-144 

23-92 

•65 

•800 

3-38 

2-65 

1-627 

13-78 

4-65 

2-156 

24-18 

•70 

•836 

3-64 

2-70 

1-643 

13-94 

4-70 

2-167 

24-44 

•75 

•866 

3-90 

2-75 

1-658 

14-20 

4-75 

2-179 

24-70 

•80 

•894 

4-16 

2-80 

1-673 

14-56 j 

4-80 

2-190 

24-96 

•85 

•922 

4-42 

2-85 

1-688 

14-82 

4-85 

2-202 

25-22 

•90 

•949 

4-68 

2-90 

1-702 

15-08 

4-90 

2-213 

25-48 

•95 

•974 

4-94 

2-95 

1-717 

15-34 

4-95 

2-224 

25-74 

1*00 

1-000 

5-20 

3-00 

1-732 

15-60 

5-00 

2-236 

26-00 

1-25 

1-118 

6-50 

3-25 

1-802 

16-90 

5-25 

2-291 

27-30 

1-30 

1-141 

6-76 

3-30 

1-816 

17-16 

5-30 

2-302 

27-56 

1*35 

1-164 

7-02 

3-35 

1-830 

17.42 

1 5-35 

2-313 

27-82 

1-40 

1-182 

7-28 

3-40 

1-843 

17-68 

5-40 

2-323 

28-08 

1*45 

1-204 

7-54 

3-45 

1-857 

17-94 

5-45 

2-334 

28-34 

1-50 

1-224 

7-80 

3-50 

1-870 

18-20 

5-50 

2-345 

28-60 

1-55 

1-245 

8-06 

3*55 

1-884 

18-46 

5‘55 

2-355 

28-86 

1-60 

1-264 

8-32 

3-60 

1-897 

18-72 

| 5-60 

2-366 

29-12 

1-65 

1-284 

8-58 

3 65 

1-910 

18-98 

5-65 

2-377 

29-38 

1-70 

1-303 

j 8-84 

3-70 

1-923 

19-24 

1 5-70 

2-387 

29 64 

1-75 

1-322 

9-10 

3-75 

1-936 

19*50 

5-75 

2-397 

29-90 

1-80 

1-341 

9-36 

3-80 

1-949 

19-76 

I 5-80 

2-408 

30-16 

1-85 

1-360 

9-62 

3-85 

1-962 

20-02 

5-85 

2-418 

30-42 

1-90 

1.378 

i 9-88 

3-90 

1-974 

20-28 

5-90 

2-428 

30-68 

1-95 

1-396 

| 10T4 

3-95 

1-987 

20-54 

j 5-95 

2-439 

30-94 

2-00 

1-414 

10-40 

4-00 

2-000 

20-80 

6-00 

2*449 

31-20 





































XI. Table of the Volume, Density and Pressure of Air at 
various temperatures. 

(Calculated from the following data : Volume of 1 lb. of air 
at constant atmospheric pressure = 14*7 lbs. per square inch, 
volume at 62 degrees Fain*, being 1 ; the density or weight is 
that of a cubic foot of air at atmospheric pressure, the pressure 
is that of a given weight of air having a constant volume, 
atmospheric pressure at 60 degrees Fahr. being 1.) 


Fahr. 

Volume. 

Density lbs. 

Pressure. 

Cubic feet. 

Compara¬ 
tive vol. 

lbs. per 
sq. in. 

Compara¬ 
tive pres. 

0 

11*583 

*881 

*086331 

12*96 

*881 

32 

12*387 

*943 

*080728 

13*86 

*943 

40 

12*586 

*958 

*079439 

14*08 

*958 

50 

1 12*840 

*977 

*077884 

14*36 

*977 

62 

13*141 

1*000 

*076097 

14*70 

1*000 

70 

13*342 

1*015 

*074950 

14*92 

1*015 

80 

13*593 

1*034 

*073565 

15*21 

1 *034 

90 

13*845 

1*054 

*072230 

15*49 

1*054 

100 

14*096 

1*073 

*070942 

15*77 

1*073 

110 

14*344 

1*092 

*069721 

16*05 

1*092 

120 

14*592 

1*111 

*068500 

16*33 

1*111 

130 

14*846 

1*130 

*067361 

16*61 

1*130 

140 

15*100 

1*149 

*066221 

16*89 

1*149 

150 

15*351 

1*168 

*065155 

17*19 

1*168 

160 

15*603 

1*187 

*064088 

17*50 

1*187 

170 

15*854 

1*206 

*063089 

17*76 

1*206 

180 

16*106 

1*226 

*062090 

18*02 

1*226 

200 

16*606 

1*264 

*060210 

18*58 

1*264 

210 

16*8d0 

1*283 

*059313 

18*86 

1 *283 

212 

16*910 

1*287 

*059135 

18*92 

1*287 


(D. K. Clark.) 



















67 


XII. Table showing - the relative variations in mercury, water 
and gas, by changes of atmospheric pressure. 


Column of 

Mercury. 

Water. 

\ 

Carbureted Hydrogen. 

A. 

B. 

C. 


A X 848-102 

A X “ 


62-355 

•42553 

X 

6-80 

9,965 

1 

13.60 

19,930 

1J4 

20-40 

29,895 

2 

27-20 

39,860 

2 X 

34 00 

49,826 

3 

40-80 

59,791 


XIII. Table showing the Pressure of the atmosphere per 
square inch and per square foot, at the following Readings of 
the Barometer. 

(Rule. —Barometer in inches X ‘4908 — pressure per square 
inch ; pressure per square inch X 144 = pressure per square 
foot.) 


Barometer in 
inches. 

Pressure per square 
inch in pounds. 

Pressure per square 
foot in pounds, 
decimals omitted. 

28-00 

13-74 

1978 

28-25 

13-86 

1995 

28‘50 

13-98 

2013 

28-75 

14-11 

2031 

29-00 

14-23 

2049 

29-25 

14-35 

2066 

29-50 

14-47 

2083 

29-75 

14-60 

2102 

30-00 

14-72 

2119 

30-25 

14-84 

2136 

30-50 

14-96 

2154 

30-75 

15-09 

2172 

31-00 

15.21 

2190 






























68 


XIY. Table to Illustrate the Chemical Change which takes 
place in Breathing. 

(The air inhaled has the common temperature of the atmos¬ 
phere, on an average about 59" F. The air exhaled has the 
temperature of the body, about 99 degrees Fahr. and contains 
a corresponding quantity of aqueous vapor, which amounts at 
each exhalation to from 1 to 134 grains.) 


Amount present in 
air of 

Air inhaled. 

Air exhaled. 

In 100 
vols. by 
measure. 

In 100 
parts by 
weight. 

In 100 
vols. by 
measure. 

In 100 
parts by 
weight. 

Oxygen - 

20-815 

23-009 

16-033 

17-373 

Nitrogen. 

79-185 

76-991 

79-587 

76-081 

Carbonic acid__ 

trace. 

trace. 

4-380 

6.546 


100. 

100. 

100. 

100. 


XV. Table of Analyses of Different Compound Gases, by 
weight. 



Carbonic 

Carbonic 


Oxide Gas. 

Acid Gas. 


C O 

co 2 

Carbon... . 

42-86 

27-27 

Oxygen -- 

57-14 

72-73 

Total... 

100. 

100. 


Marsh Gas. 

Olefiant Gas. 


ch 4 

C 2 II 4 

Carbon__ 

74-95 

85-68 

Hydrogen.... 

25-05 

14-32 

Total_ 

100. 

100. 



















































G9 


Air. 

Oxygen......23.00 

Nitrogen......77. 

100 . 

Sulphurated Hydrogen. 

H, S 


Sulphur.....04-12 

Hydrogen...........5 - 88 


100 . 


XYI. Table of Analyses of Coal Gas from Cannel Coal. 



^ Manchester 
~ gas. 

U 

3 

& , 

V m 

& 

§ 

C3 

S 

(2) 

1 

Rochdale 

gas. 

London gas. 

w> 

m 

1 

6 

Hydrogen. 

45-58 

52-71 

53-44 

35-94 

39-69 

Marsh Gas_ 

34-90 

31-05 

29-87 

41-99 

36-27 

Carbon monoxide (carbonic 






oxide)__ 

6-64 

4-47 

5-86 

10-07 

9-33 

Olefines_ 

6-46 

11-19 

10-83 

10-81 

8-95 

Nitrogen_ 

2-46 




2-94 

Carbon dioxide (carbonic 






acid)_ 

3-67 

0-58 


1-19 

2-49 

Oxygen-- - 





•33 

Sulphureted hydrogen _ _. 

0-29 





Total_ 

100. 

100. 

100. 

100. 

100. 





































70 


XVII. Table of Analyses of Coal Gas from Bituminous Coal. 



7- 

u 

o 

3 

(1) 

■L 

ci 

M 

o 

T3 

© 

J 

(2) 

&P 

o 

~ QQ 

<v zi 

2 wj 
*53 

Cardiff gas. 

Hydrogen.. 

| 50-05 

51-24 

44-00 

47-32 

Marsh Gas__ 

32-87 

35-28 

38-40 

38-21 

Carbon monoxide (carbonic 





oxide) ___ 

12-89 

7-40 

5-73 

7-79 

Olefines_ 

3-87 

3-56 

7-27 

4-41 

Nitrogen.. 


2-24 


1-83 

Carbon dioxide (carbonic 





acid)... 

0-32 

0-28 

4-23 

0-13 

Oxygen... 



0-37 

•31 

Total..... 

100. 

100. 

100. 

100. 


XVIII. Table of the Expansion of Air by Heat. (By Magnus 
and Regnault.) 


Degs. Fahr. 

Volume. 

| 

Begs. Fahr. 

Volume. 

32 

10,000 

130 

11,996 

40 

10,160 

140 

12,199 

50 

10,366 

150 

12,403 

60 

10,570 

160 

12,606 

70 

10,773 

170 

12,810 

80 

10,977 

180 

13,014 

90 

11,181 

190 

13,218 

100 

11,385 

200 

13,421 

110 

11,588 

210 

13,625 

120 

11,792 

212 

13,666 


And the volume of any other temperature, t, will be 
10,000 x 4 l 9 + < - 


459 -J- 452 











































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0* 


11 
















































XX. Table showing barometric readings corresponding with 
different altitudes, in French and English measures. 


< 

Meters. 

P Reading of 
g barometer. 

a; 

< 

Feet. 

C 

a> 

tx a; 

.s s 

^3 o 

03 H 
a> 5 

^ rO 

Inches. 

6 

+5 

Meters. 

? Reading of 

g barometer. 

*T) 

g Altitude. 

hH 

n Reading of 

jjf barometer. 

75 

0 

762 

o- 

30- 

1147 

660 

3763-2 

25-98 

21 

760 

68-9 

29-92 

1269 

650 

4163-3 

25-59 

127 

750 

4167 

29-52 

1393 

640 

4568-3 

25-19 

234 

740 

767-7 

29-13 

1519 

630 

4983-1 

24-80 

342 

730 

1122-1 

28-74 

1647 

620 

5403-2 

24-41 

453 

720 

1486-2 

28-35 

1777 

610 

5830-2 

24-01 

564 

710 

1850-4 

27-95 

1909 

600 

6243- 

23-62 

678 

700 

2224*5 

27-55 

2043 

590 

6702-9 

23-22 

793 

690 

2599-7 

27-16 

2180 

580 

7152-4 

22-83 

909 

680 

2962-1 

26-77 

2318 

570 

7605-1 

22-44 

1027 

670 

3369-5 

26-38 

2460 

560 

8071- 

22-04 


1 meter = 3-2808992 feet = 39'3707904 inches. 

XXI. Table of comparative readings of thermometer on the 
different scales—Centigrade, Reaumur and Fahrenheit. 


C 

R 

F 

C 

R 

F 

C 

R 

F 

C 

R 

F 

100 

80- 

212* 

75 

60- 

167- 

50 

40- 

122- 

25 

20- 

nr?* 
i l 

99 

79-2 

210-2 

74 

59-2 

1652 

49 

39-2 

1202 

24 

19-2 

752 

98 

78-4 

2084 

73 

58-4 

163-4 

48 

38-4 

118-4 

23 

18-4 

734 

97 

77-6 

2066 

72 

57-6 

161-6 

47 

37-6 

116-6 

22 

17-6 

71-6 

96 

76-8 

204 8 

71 

56-8 

159-8 

46 

36-8 

114-8 

21 

16-8 

69 8 

95 

76" 

203- 

70 

56- 

158- 

45 

36" 

113* 

20 

16- 

68* 

94 

752 

201-2 

69 

55-2 

156-2 

44 

35-2 

111-2 

19 

15-2 

66-2 

93 

74-4 

199-4 

68 

54 4 

154-4 

43 

34-4 

109-4 

18 

14-4 

64-4 

92 

73‘6 

197-6 

67 

536 

152-6 

42 

33-6 

107-6 

17 

136 

62-6 

91 

72-8 

195-8 

66 

52-8 

150-8 

41 

32-8 

105-8 

16 

12-8 

60-8 

90 

72- 

194- 

65 

52- 

149- 

40 

32- 

104- 

15 

12- 

59- 

89 

71-2 

1922 

64 

51-2 

1472 

39 

31-2 

102-2 

14 

11*2 

57-2 

88 

70-1 

1904 

63 

50-4 

145-4 

38 

304 

100-4 

13 

10-4 

55-4 

87 

69-6 

188-6 

62 

49-6 

1436 

37 

29-6 

98-6 

12 

9-6 

53-6 

86 

68'8 

186-8 

61 

48-8 

141-8 

36 

28-8 

96-8 

11 

8-8 

51-8 

85 

68- 

185- 

60 

48- 

140- 

35 

28- 

95- 

10 

8- 

50- 

84 

67-2 

183 2 

59 

47-2 

138-2 

34 

27-2 

93-2 

9 

7-2 

48-2 

83 

66-4 

181-4 

58 

46-4 

136-4 

33 

26-4 

91*4 

8 

6-4 

46-4 

82 

65-6 

179-6 

57 

45-6 

134-6 

32 

25-6 

89*6 

7 

5-6 

44 6 

81 

64-8 

177-8 

56 

44-8 

132-8 

31 

24-8 

87-8 

6 

4-8 

42-8 

80 

64-0 

176- 

55 

44- 

131* 

30 

24- 

86- 

5 

4- 

41- 

79 

632 

1742 

54 

432 

129-2 

29 

23 2 

84-2 

4 

3-2 

392 

78 

62-4 

172-4 

53 

42-4 

127-4 

28 

22-4 

82-4 

3 

2-4 

37-4 

77 

61-6 

170-6 

52 

41-6 

125-6 

27 

21-6 

80-6 

2 

1*6 

35-6 

76 

60-8 

168-8 

51 

40-8 

123-8 

26 

20-8 

78-8 

1 

08 

33-8 

1 













































Miles per 

<K35Cni^o5Mi-iooGo<!050itMXK)M hour. 


n 


XXII. Table of velocities and pressures of Air. 

Let P = pressure of air in pounds per square foot. 
Let V = velocity in miles per hour. 


Then P = ? 


V 2 


200 


Feet per 
second. 

Pounds 
per square 
foot. 

Miles per 
hour. 

Feet per 
second. 

Pounds 
per square 
foot. 

Miles per 
hour. 

Feet per 

second. 

Pounds 

per square 

foot. 

1-46 

•005 

18 

26-40 

1-620 

35 

51-33 

6-125 

2-93 

•020 

19 

27-86 

1-805 

36 

52-80 

6-480 

4-40 

•045 

20 

29-33 

2-000 

37 

54-26 

6-845 

5-86 

•080 

21 

30-80 

2-205 

38 

55-73 

7-220 

7*33 

•125 

22 

32-26 

2-420 

39 

57-20 

7-605 

8*80 

•160 

23 

33-73 

2-645 

40 

58-66 

8-000 

10-26 

•245 

24 

35-20 

2-880 

41 

60-13 

8-405 

11-73 

•320 

25 

36-66 

3125 

42 

61-60 

8-820 

13-20 

•405 

26 

38-13 

3-380 

43 

63-06 

9-245 

14-66 

•500 

27 

39-60 

3-645 

44 

64-53 

9-680 

16-13 

•605 

28 

41-06 

3-920 

45 

66 00 

10-125 

17-60 

•720 

29 

42-53 

4-205 

46 

67-46 

10-580 

19-06 

•845 

30 

44-00 

4-500 

47 

68-93 

11-045 

20-53 

•980 

31 

45-46 

4-805 

48 

70-40 

11-520 

22-00 

1-125 

32 

46-93 

5-140 

49 

71-86 

12-005 

23-46 

1-280 

33 

48-40 

5-445 

50 

73-33 

12-500 

24-93 

1-445 

34 

49-86 

5-780 

60 

88-00 

18-000 


























74 


XXIII. Table showing’ the quantity of g*as in cubic feet 
obtained from coal. 


Locality where Coal is mined. 

Specific 
Gravity of 
Gas. 

Cubic feet of 
gas obtained per 
ton of Coal. 

Weight in 
pounds of gas 
per ton of 
Coal. 

Boghead.. 

•752 

15,000 

866 

Capeldrae___ 

•577 

14,400 

638 

Lesmahagow_ 

•618 

13,200 

627 

Arniston... 

•626 

12,600 

606 

Newcastle-on-Tyne_ 

•475 

11,648 

423 

South Wales... 

•737 

11,424 

645 

Pelaw ____ 

•444 

11,424 

389 

Pelton... 

•437 

11,424 

387 

Bickerstaff ___ 

•475 

11,424 

415 

Wigan.... 

•528 

11,400 

461 

Garesfield_ 

•398 

10,500 

321 

Powell’s South Wales_ 

•459 

10,165 

357 

Forest of Dean__ 

*360 

10,133 

279 

S. Staffordshire... 

•320 

9,600 

235 

Derby Deep Main_ . 

•424 

9,400 

308 

Derby Soft Coal_ 

•528 

7,500 

303 

Leeds... 

•530 

6,500 

264 


XXIV. Table Showing- the Conversion of Column of Water 
to Column of Mercury and Fire-damp. 


Water. 

Mercury. 

Fire-damp. 

1 

0-0738 

1,465 

2 

0*1474 

2,930 

3 

0-2211 

4,395 

4 

0-2948 

5,861 

5 

0-3685 

7,327 

6 

0-4421 

8,792 

ry 

i 

0-5158 

10,258 

8 

0-5895 

11,723 

9 

0-6632 

13,189 








































XX\ . Table showing the relative weight of water and air at various temperatures, with deductions made therefrom. 


75 


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76 


CHAPTER VI. 

LEGISLATION ON THE SUBJECT OF MINE VENTILATION IN THE 
UNITED STATES AND FOREIGN COUNTRIES. 

In order to have an intelligent comprehension of the whole 
question of mine ventilation, it appears desirable, indeed neces¬ 
sary, to review, at least briefly, some of the laws which have 
been enacted in different countries on the subject for fhe pro¬ 
tection of miners from dangers associated with the noxious 
gases which so commonly pervade the atmosphere of coal 
mines. By doing this the reader will see how the matter has 
been considered by the mining authorities of different coal pro¬ 
ducing countries. 

The legislators of those countries where coal mining is car¬ 
ried on extensively have acted wisely and humanely in enact¬ 
ing laws for the safety of those engaged in the operations. 

In making extracts from the various mining laws, we will 
limit their extent as much as possible, and only make refer¬ 
ence to matters that may be considered of essential import¬ 
ance. 

Prussia. 

We will first give some particulars with regard to Prussia, 
where the section of the air-ways is dependent upon the quan¬ 
tities of air necessary for the ventilation of the whole mine, 
including different splits, calculated upon a velocity of 13 feet 
per second for the fresh air-current, and of 22 feet per second 
for the return air-current. 

The ventilation of fire-damp mines must be sufficient to pre¬ 
vent the accumulation of fire-damp under ordinary circum¬ 
stances, and to keep all parts of the mine constantly in a safe 
condition to be entered and worked. 

Special ventilation plans are to be prepared in fire-damp 
mines. The use of ventilating furnaces is permitted only on 
condition that the furnace be fed with fresh air. The quantity 
of fresh air per minute is to be at least 2 cubic meters = 71 
cubic feet per minute for each man of the largest force working 
underground, and a horse is counted to be equal to four men. 

All fire-damp mines must have stations for the measurement 
of the air-currents. Such stations to be given on the working 
plan and on the ventilation plan of the mine. Air-doors are to 
be self closing. The Prussian Fire-Damp Commission in their 
report on the ventilation of fiery mines recommend the ascen¬ 
sional principle of ventilation and say: “ The ventilation should 
be managed in such a way that the current of fresh air de¬ 
scends from the surface by the shortest way, until it reaches the 
level of the working vein, and afterwards each current should 
flow in an upward direction through the different sections of 
the miqe.” 


77 


England. 

As regards the mining laws of England we may allow our¬ 
selves to quote Professor Arthur Lakes, who has recently re¬ 
turned from a visit to that country, and who in the Mining 
Industry for Nov. 30th, 1893, says : “ There is no class of men 

in the world so protected by law as the English coal miner.” 
A good many Englishmen are of the opinion that coal opera¬ 
tions are over-legislated, but although English mine super¬ 
intendents have regarded mining legislation as unnecessarily 
particular—perplexing, and harassing—yet there can be no 
doubt the effect of it in recent years has been to minimize the 
dangers of coal mining, especially under the head of colliery 
explosions. In England the law requires that “an adequate 
amount of ventilation shall be constantly produced in every 
mine to dilute and render harmless noxious gases to such an 
extent that the working places of the shafts, levels, stables, 
and workings of the mine, and the traveling roads to and from 
those working places, shall be in a fit state for working and 
passing therein. Now if this law was thoroughly carried out, 
there would be no explosions of fire-damp. No specified quan¬ 
tity of air is required by the act, but the first general rule as 
here, quoted requires that it shall be adequate. The law with 
respect to the construction and use of safety lamps is very strict 
and explicit, and so it is with regard to the use of explosives in 
mining. The framers of this act seem to have attached much 
importance to the changes of the weather for the law requires 
that a barometer and thermometer shall be placed above 
ground in a conspicuous position near the entrance to the 
mine. 


Nova Scotia. 

The mining law of Nova Scotia is copied in a great measure 
from that of England. The first general rule requires that “an 
adequate amount of ventilation shall be constantly produced in 
every mine to dilute and render harmless noxious gases, to such 
an extent that the working places of the shafts, levels, stables, 
winzes, sumps and workings of such mine, and the traveling- 
roads to and from such working places, shall be in a fit state 
for working and passing therein. In every mine in which in¬ 
flammable gas has been found within the preceding twelve 
months a competent person or persons holding certificates as 
underground managers, overmen, or sliotfirers, who shall be 
appointed for the purpose, shall inspect with a safety lamp that 
part of the mine being or intended to be worked, and the road¬ 
ways leading thereto, within five hours of the time of each 
shift commencing work, and if inflammable gas has been found 
within the preceding three months, then, within three hours of 
the time of commencing work, shall make a true report to the 
manager, underground manager, or overman, at the time in 


78 


charge of the pit, of the condition thereof as far as ventilation 
is concerned; and a workman shall not go to work in such part 
until the same and the roadways leading thereto are stated to 
be safe.” The law likewise lays down particular rules for the 
use of explosives in mines, and the shot-firer or fire-boss is re¬ 
quired to pass an examination and be in possession of a certi¬ 
ficate of competency before he is appointed to take charge of 
the blasting* or shot-firing* in a mine. 

Victoria. 

With regard to the ventilation of mines in Victoria, we find 
it stated in the General Reports of the Mining Inspectors for 
1892, that the sooner the law fixes the amount of air per minute 
to be sent in for every man w*orking* in the mine, the better it 
will be for the employes. 

In certain respects the laws of some of the States of America 
are in advance of those of other countries, and before closing 
this chapter we will give illustrations of some of the require¬ 
ments of the law in different states of the Union. 

Anthracite Law of Pennsylvania. 

For example, with regard to furnaces, the Anthracite Law of 
Pennsylvania enacts that “It shall not be lawful to use a fur¬ 
nace for the purpose of ventilating any mine wherein explosive 
gases are generated.” 

Not more than 75 persons shall be employed at the same 
time in any one current or split of air. 

The quantity of air shall not be less than 200 cubic feet a 
minute and in no case in mines generating explosive gas shall 
the velocity exceed 9 feet per second. 

All ventilating doors shall fall-to of themselves. 

Bituminous Law of Pennsylvania. 

The Bituminous Law of Pennsylvania enacts that not less 
than 100 cubic feet of air per minute shall be provided for each 
person employed in a mine, but, where fire-damp has been 
detected, the minimum shall be 150 cubic feet per minute. Not 
more than 65 persons shall be allowed to work in one current. 
No accumulation of gas shall be allowed to exist in the worked 
out part's of a mine. 

The Davy and Clanny lamps are prohibited for general work 
unless protected by a metallic shield. The lamps used shall be 
the property of the operator. 

Ohio. 

In 11 le State of Ohio the amount of ventilation to be provided 
shall not be less than 100 cubic feet per minute for each person 
employed. All mines generating fire-damp shall be kept free 
from standing gas. 


79 


Iowa. 

The quantity of air to be provided for the mines in the State 
of Iowa shall be not less than 100 cubic feet per minute for 
each person employed, and 500 cubic feet per minute for each 
mule. 


Washington. 

In the State of Washington the amount of air in circulation 
in coal mines shall in no case be less than 100 cubic feet for 
each person per minute. 


Tennessee. 

In the State of Tennessee it is enacted that an adequate 
amount of ventilation, not less than fifty-five cubic feet per 
second of pure air, or thirty-three hundred cubic feet per 
minute for every fifty men at work in the mine shall be pro¬ 
vided. The intake air-way shall not be less than 20 square feet 
area and the return air-way not less than 25 square feet. 

West Virginia. 

In West Virginia ample means of ventilation shall be pro¬ 
vided affording not less than 100 cubic feet of air per minute 
for each and every person employed in the mine. 

Kentucky. 

The law of the State of Kentucky requires that all mines 
shall be kept free of standing gas, and the quantity of air to be 
provided shall not be less than 100 cubic feet per man per 
minute. 


Alabama. 

In the State of Alabama there shall be provided sufficient 
ventilation for each and every person employed in the mine, 
which shall be circulated around the main headings, cross¬ 
headings, and working places to. an extent that will dilute, 
render harmless and carry off noxious and dangerous gases 
generated therein. 


Kansas. 

The air to be provided in the coal mines of Kansas is 100 cubic 
feet per minute per person in veins 3 feet thick or over. The 
mines are to be kept free of standing gas. Shotfirers are to be 
appointed, whose duty it will be to fire shots once a day, when 
the mines are in operation. The coal shall be properly under¬ 
mined before the shots are fired. 


80 


Arkansas. 

According to the law of the State of Arkansas the amount of 
air to be provided is not less than 100 cubic feet per man, per 
minute. 

A bore-hole is to be kept 20 feet in advance of the face of a 
working place going towards an abandoned mine suspected of 
containing inflammable gas or water. 

Indiana. 

In the State of Indiana there shall be provided a sufficient 
amount of ventilation affording not less than 100 cubic feet per 
minute for each and every person employed and 300 cubic feet 
per minute for each mule, horse or other animal used in the 
mine. The air currents shall be split so as to give separate 
currents to at least every 50 persons at work. 

Territories. 

In the mines of the Territories of the United States, an ade¬ 
quate amount of ventilation shall be provided, not less than 55 
cubic feet of pure air per second or 3,300 cubic feet per minute 
for every 50 men at work. In no case shall a furnace shaft be 
used as, or for the purposes of this act, be deemed an escape- 
shaft. 


APPENDIX. 


QUESTIONS AND ANSWERS ON SUBJECTS RELATING TO MINE 
VENTILATION, ATMOSPHERIC AIR AND GASES, MAINLY SE¬ 
LECTED FROM VARIOUS AMERICAN EXAMINATIONS FOR MINE 
INSPECTORS AND MINE FOREMEN. 

1. What is meant by the area of an air course? 

Ans. It means the superficies or number of square units— 
usually feet—contained in the section of a road. 

2. What is meant by the section of a road? 

Ans. A cross-cut made at right angles to its plane. 

3. What is meant by the perimeter of a road ? 

Ans. The circumference or measure of the outline of the 
section. 

4. What is meant by the rubbing’ surface of a road? 

Ans. The superficial area of the walls—that is the sides, 
roof and floor—usually reckoned in square feet, and is calculated 
by multiplying the perimeter by the length. 

5. What is the perimeter of a road 6 feet high and 7 feet 
wide ? 

Ans. 6 + 6 + 7 + 7 = 26. 

6. What is the area of a road measuring 7 feet 3 inches by 6 
feet 6 inches ? 

Ans. By cross-multiplication, 


7 3 

6 6 
3 7 6 

43 6 - 

47 1 6 = 47i feet. 

By decimals, 

7’2o 

6*5 

3625 

4350 

47*125 = 47i feet. 

7. What is the rubbing surface of a road 8 feet 6 inches 
wide, 6 feet 9 inches high and 3000 feet long ? 

Ans. 8 ft. 6 in. -f 8 ft. 6 in. + 6 ft. 9 in. -f 6 ft. 9 in. = 30 ft. 
6 in. the perimeter and this multiplied by 3000, the length =; 
91,500 sq. ft. the rubbing surface, 






82 


8. How is the quantity of air passing along an underground 
road ascertained ? 

Ans. By observing with an anemometer the velocity of the 
flow of the current, by measuring the area of the section of the 
road, and multiplying the two together. 

9. If the velocity of the air be 375 ft. a minute, and the road 
•has an area of 48 ft. what is the quantity of air passing? 

Ans. 375 X 48 = 18,000 cubic feet per minute. 

10. If the velocity of the air in an upcast shaft 14 ft. dia¬ 
meter be 1,100 feet a minute, how much air is there returning 
from the mine ? 

Ans. The area of the shaft is found by squaring the diameter 
and multiplying by *7854; 14 X 14 X '7854 = 153-9384 area, 
then 153-9384 X 1,100 = 169,332 cubic feet of air per minute. 

11. If with a water-gauge of half an inch the quantity of air 
passiug be 24,000 cubic feet, how much will pass when the 
water-gauge reads 3 inches ? 

Ans. The quantity is according to the square root of the 
pressure, or the water-gauge. By Table X. of Chap. V. it will 
be seen that the square root of one-half = "707, and the square 
root of 3 = 1*732; then say if -707 gives 24,000, what will 1-732 

give, thus--= 58,795 cubic feet. 


12. If air has a velocity of 550 feet a minute, how many 
miles an hour is it equal to? 

Ans. There are 1,760 yards or 5,280 feet in a mile : the velo¬ 
city of the ahi per hour will be 550 x 60 = 33,000 feet, then 

——— = 6*24 miles an hour. 

5,280 ^ 


13. If in furnace ventilation the downcast has a tempera¬ 
ture of 65 degs., and the upcast 140 degs., the depth of the 
shafts being 1,500 feet, what is the pressure of the ventilation? 

Ans. By reference to table XIX., Chap. V., it will be seen 
that the weight of air at 65 degs. at a depth of 1,500 feet will 
be 113-812 lbs., and at 140 degs. it will be 99-562 lbs.; the dif¬ 
ference between these tw<5 is 14*25 lbs., which is the amount of 
the pressure. 

14. If the water-gauge be in., what is the pressure per 
square foot? 

Ans. 3*5 X 5*2 = 18 2 lbs. 

15. If the quantity of air passing be 60,000 cubic feet a 
minute, and the water gauge be 2 inches, what is the amount 
of the horse-power producing the ventilation? 


Ans. 


60,000 X 2 X 5-2 
33,000 


19 nearly. 


16. What quantity of air will be necessary to ventilate a 
mine in which 200 men are engaged? 

£ns. According to the Anthracite Mine Law of Pennsyl- 





vania, 200 cubic feet of air per man per minute is the minimum 
quantity to be provided; the inspector of the 8th Anthracite 
district says in his report for 1892, that “ most of the fiery 
mines require much larger volumes than the minimum quan¬ 
tity provided for in the Act of Assembly.” 

17. How much will the ventilating pressure have to be in¬ 
creased if the quantity of air be doubled? 

Ans. Four times. 

18. How much will the power have to be increased if the 
quantity be increased from 10,000 to 15,000? 

Ans. According to the cube of 1% = 1*5 X 1*5 X 1*5 =3-375 
times. 

19. What is the horse-power required to drive a fan produc¬ 
ing 60,000 cubic feet of air per minute, with a water-gauge of 
1*7 in.? If the quantity be increased to 100,000 cubic feet per 
minute, how much additional power would be required ? 

Ans. The horse-power is found thus : 


60,000 X 1*7 X 5-2 
33,000 


16 horse-power. 


The power is according to the cube of the quantity, therefore, 
after canceling the noughts, the power will be increased from 

6 3 to 10 3 = 216 to 1,000 and - 1,QQQ = 4*63 times. 

216 


20. How much more resistance does an air-current en¬ 
counter when traveling at 600 feet per minute than at 500 
feet per minute, size of air-way being unchanged? If the 
water-gauge is *76 inch at the lower speed, what would it be at 
the higher? 

Ans. As the resistance is according to the square of the 
velocity, it would be in proportion to 5 squared and 6 squared 
= as 25 is to 36, which would be in proportion to these figures, 
thus : 

25 : *76 :: 36 = 1*09. 

21. Given an arched air-way 10 feet diameter, with semi¬ 
circle arch, springing five feet from the floor, velocity of air 
500 feet per minute, what will be the quantity of air in cubic 
feet per minute? 

Ans. The area of the arch is found thus : 


10 X 10 X *7854 
2 

Below the springing, thus: 

5X 10 = 


39-27 ft. 


50 

89-27 


89-27 X 500 = 44,635 cubic feet per minute passing. 

22. What is the comparative friction or resistance of the air 
when traveling at the same velocity through an air-course 8 
feet square, and one 12 feet by 5 feet 4 in.? 






84 


Ans. The friction or resistance in this case will be according 1 
to the rubbing surface or perimeter ; in the road 8 feet square, 
it will be 8 8 -f- 8 + 8 = 32 ; in the other road it will be 12 

-f-12 -f- 5 ft. 4 in. -f- 5 ft. 4 in. = 34 ft. 8 in. The friction will 
be in the proportion of 32 to 34%. 

23. If a ventilating current of 27,500 cubic feet per minute 
is circulating in a mine with 1*8 in. water-gauge, what will the 
water-gauge be if the quantity of air is increased to 50,000 
cubic feet per minute with same conditions in the mine? 

Ans. The water-gauge will be according to the square of the 
quantities, thus: 

27,500 8 : 1*8 :: 50,000 2 = 5*9 water-gauge. 

24. How many cubic feet of air will pass per minute through 
an air course 5 ft. by 7 ft. when the current is traveling at the 
rate of 20 yards in 15 seconds ? 

Ans. 20 yards in 15 seconds will be equal to 80 yards in a 
minute : 80 X 3 = 240 ft.; 5 X 7 = 35, and 35 X 240 = 8,400 
cubic feet per minute. 

25. The velocity of the air is 9 feet per second, and the area 
of the road is 70 ft., what is the quantity of air passing? 

Ans. 9 X 60 X 70 = 37,800 cubic feet per minute. 

26. If the air-road be doubled in length, how much will the 
resistance be increased ? 

Ans. It will be doubled. 

27. If the ventilating pressure be indicated with a water- 
gauge of T V<hs of an inch, when the quantity of air passing is 
20,000 cubic feet, what will the quantity be when, by additional 
appliances, the water-gauge is increased to inches? 

Ans. The quantity will be in accordance with the square 
root of the water-gauge. T 8 ^ = -8 ; 1% = 1-5. By referring to 
table X., Chap. V., it will be seen the square root of *8 = *894, 
and of 1*5 = 1*224. Then, as *894 is to 20,000 so is 1*224 to 
27,382 cubic feet per minute. . 

28. What is meant by dividing one current of air into two 
equal splits? 

Ans. It means this : supposing there is one current of air 
going round the mine through a road 6 ft. square and 1,600 yards 
long, when divided into two equal splits there will be two roads 
each 800 yards long and 6 ft. square. 

29. What are the advantages and disadvantages of a dumb- 
drift ? 

Ans. The advantage in using this slope drift is that the 
return air does not go over the furnace, and there is therefore 
no danger of an explosion thereby; the disadvantage is that 
the heated air column is not so long and consequently the 
ventilating pressure is less, and the air used to keep up the 
furnace is not utilized in the mine. 

30. If a dumb-drift rise 35 per cent, for 70 yards, what height 
will it come out in the upcast shaft above the furnace? 

Ans. It will come into the shaft at 2££ yds. above the 
furnace. u 


85 


81. Suppose the shaft to be 800 yards deep, and the tempera¬ 
ture in the upcast to be 200°, what pressure is lost by a dumb- 
drift coming into the upcast 22| yards above the furnace? 

Ans. The weight of air, by Table XIX., Chap. V., at a depth 
of 900 feet, at the temperature of 200° = 54-298 lbs. at the reduced 


depth it will be --.22_of this = 



which is the amount of pressure lost under the conditions stated. 

82. If the furnace be supplied with 8,000 feet of air per 
minute, what additional friction does it put on the air ? 

Ans. That depends on the quantity of air passing through 
the mine ; the friction will be according to the square of the 
quantity. If 40,000 ft. go through the mine, 48,000 will go up the 
shaft; the friction will, therefore, be as 40 2 is to 43 2 or as 16 to 
18 f 

33. What is the difference between natural and artificial 
ventilation ? 

Ans. By natural ventilation is meant the current produced 
naturally by the changes in temperature of the outer and inner 
air, or the air in and out of the mine. In the outer air 

will be colder than the air of the mine, so that it happens in 
shallow mines, where natural ventilation is used, the air atone 
time of the year will flow in one direction, and at other times 
in the opposite direction. Natural ventilation is thus uncertain 
and irregular. By artificial ventilation is meant the regular 
application of some motor to maintain an air-current, as by 
furnace or fan, by the working of which one end of the air- 
current is rarefied and a ventilating pressure produced. 

34. Is furnace ventilation better in winter than in summer? 
If so, why? 

Ans. It is better in winter, because the downcast air is 
colder and heavier in winter than in summer. The air of the 
mine is pretty constant all the year round ; therefore, with the 
same amount of firing there will be a greater difference in the 
temperature of the two shafts in winter and consequently a 
greater pressure. 

35. In using furnaces, which will give the largest ventilating 
pressure, deep or shallow shafts? 

Ans. Deep shafts—the pressure being in accordance with 
the difference of temperature multiplied by the depth, 

36. What is the extreme pressure in the ventilation that may 
be obtained by furnace and fan? 

Ans. If in furnace ventilation we take the temperature of 
the air in the downcast to be 50 degs. and the upcast at 200 
degs., by table VIII., Chap. V., it will be seen that the weight 
of a foot of air at 



50 degs. = -0781113 lb. 
200 degs. - -0603318 lb. 
Difference = -0177795 It). 



80 


Then the pressure will be found to be at the following depths 
viz: 

At 000 ft. = 10*06 fbs. per square foot. 

At 1200 ft. — 21*83 lbs. per square foot. 

At 1800 ft. = 32*00 Tbs. per square foot. 

At 2400 ft. = 42*07 lbs. per square foot. 

The greatest pressure the writer has seen noted in the actual 
working of a fan is that at Prosper No. 1 Colliery, Westphalia, 
where 10*7 inches have been recorded, which is equal to a 
pressure of 55*64 lbs. per square foot. 

37. Can a greater pressure be obtained in a large shaft than 
in a small one? 

Ans. No, the ventilating pressure does not depend on the 
sizes of the shafts, for, as J. J. Atkinson says, “ whatever may 
be the relative sizes of the shafts, the air in the one will balance 
that in the other if the density of the air is the same in each ; 
this may be termed the pneumatic paradox.” 

38. What is meant by the pneumatic paradox ? 

Ans. It may be compared to the hydrostatic paradox, which 
means that the pressure on the bottom of a vessel full of liquid 
depends neither on the form of the vessel nor on the quantity 
of the liquid, but only on the height of the level of the liquid 
above the bottom ; in the same way neither the size nor form of 
the air-shafts which act as the downcast or upcast respectively 
alter the pressure at the bottom of the pits. The pressure is ob¬ 
tained only by altering the density of the air in the two shafts. 

39. In erecting a ventilating* fan or furnace, what points 
should be considered with respect to safety ? 

Ans. The fan should be erected in such a position, and 
placed under such conditions as will tend to insure its being 
uninjured by an explosion ; and in furnace ventilation, where 
there is inflammable gas, the furnace should be provided with 
a dumb-drift. These conditions are enforced by the 1887 Min¬ 
ing* Act of Great Britain. 

40. Are furnaces admissible in all cases for the ventilation 
of coal mines? 

Ans. No. Their use is forbidden by the Anthracite Mining 
Law of Pennsylvania, for the purpose of ventilating any mine 
wherein explosive gases are generated. 

41. Give reasons showing the superiority of mechanical 
ventilation over furnace ventilation. 

Ans. A mechanical ventilator is more cheaply worked than 
a furnace; being placed on the surface, it can be readily in¬ 
spected at any time ; the amount of the ventilation can be 
regulated, so as to increase or decrease the air-current as re¬ 
quired at any time ; there is no danger from fire as with a fur¬ 
nace ; there is no danger from an explosion of gas as with a 
furnace ; there is no sulphuric acid engendered in the upcast, 
as is often the case with a furnace, which does so much damage 


87 


to tubbing, etc.; the workmen can do repairs in the shaft with 
out disturbing the ventilation in the case of a mechanical venti¬ 
lator, whereas they cannot do so with a furnace on.account of 
the smoke. 

42. When was the steam jet first applied as a means of pro¬ 
ducing ventilation in mines ? 

Axs. It was first applied in 1835, and the introduction of it 
was due to Mr. Goldsworthey Gurney. 

43. How does the steam jet act in producing a current of 
air? 

Ans. Its action has been explained in various ways (See 
Steam Jet, Chap. II.), but it may be sufficient to say here that 
steam is blown off perpendicularly up into the upcast shaft, at 
high pressure, from small orifices made in pipes, and the force, 
temperature and aqueous vapor aid in rarefying the ascending 
air. 

44. Does it signify where the jets are placed in the upcast? 

Ans. According to the late Mr. Nicholas Wood, who made 

elaborate experiments at a large number of collieries in the 
North of England in 1853, “On the relative value of the fur¬ 
nace and the steam jet”—“there does not appear to be any 
great difference in the mechanical effect, whether the jets are 
placed at the top or bottom of the pit.” 

45. How is it that the steam jet is not more frequently used 
in the ventilation of coal mines at the present time? 

Ans. Because experiments have shown that in point of 
economy it has no comparison with other systems of producing 
air-currents. 

46. How many feet of air should be mixed with one of fire¬ 
damp so as to render it harmless? 

Ans. Thirty to forty. 

47. Where should safety-lamps be used? 

Ans. This may be answered by quoting what is enacted by 
the Anthracite Mine Law of Pennsylvania. By rule 9 of that 
Act we learn that “In every working approaching anyplace 
where there is likely to be an accumulation of explosive gases, 
or in any working in which dang*er is imminent from explosive 
gases, no light or fire other than a locked safety-lamp shall be 
allowed or used.” The reader must acquaint himself with what 
is required in this respect by the law of the State or country 
in which he is engaged. 

48. What precautions are necessary in blasting or firing shots 
in coal mines likely to contain inflammable gas? 

ANS. Judgment should be exercised in the placing and direc¬ 
tion of the hole : care should be taken in ramming, tamping or 
stemming the hole with suitable material: blasts should not be 
let off unless the coal is undermined. By Rule 11 of the An¬ 
thracite Mine Law of Pennsylvania it is required that “No 
blast shall be fired in any mine where locked safety-lamps are 
used except by permission of the mine foreman or his assistant, 


68 


and before a blast is fired, the person in charge must examine 
the place and adjoining places and satisfy himself that it is safe 
to fire such blast, before such permission is given.” By General 
Rule 12 of the Coal Mines Regulation Act, 1887, of Great Bri¬ 
tain, it is enjoined that “ in places likely to contain either ac¬ 
cumulations of ga§ or coal-dust, a shot shall not be fired unless 
the explosive is so used with water or other contrivance as to 
prevent it inflaming gas, or is of such a nature that it cannot 
inflame gas.” 

49. Will blasting by gunpowder cause an explosion ? 

Ans. Although the ordinary black powder is the best explo¬ 
sive for blasting coal, it gives off a certain amount of flame on 
explosion, and if there be any gas feeders it will ignite them at 
nearly every blast. 

50/Will "blasting by dynamite cause an explosion of fire¬ 
damp ? 

Ans. This explosive in its various forms is safer and less 
liable to ignite the gas than gunpowder, but as Mr. Williams, 
the Inspector for the 4th Anthracite District of Pennsylvania, 
says : “ If a blast has less work to perform than is necessary 

to consume the energy of the explosive, it generates heat 
enough to ignite the fire-damp.” 

51. What are blown-out shots, and what dangers are con¬ 
nected with them ? 

Ans. Blown-out or gunned shots are such blasts as blow out 
the stemming or tamping without bringing down the coal, and 
are dangerous because under certain conditions they will pro¬ 
duce explosions. It is now accepted that in some mines a 
blown-out shot, where coal-dust is present, will without any 
fire-damp cause an explosion. (See Chap. V.) 

52. Which is more difficult to ventilate, an upbrow or down- 
brow place—that is, a rise or dip place? What forces are 
against or in favor of each case? 

Ans. An upbrow is more difficult to ventilate than a down- 
brow ; the light air always finds its way upwards, and the 
heavy air descends ; fresh air is heavier than return air ; these 
facts are in favor of ventilating the downbrow, and against the 
upbrow. 

53. In driving a single place or underground channel in 

advance of the underground workings, how would you carry 
the air to the face ? ' —^ 

Ans. By putting up brattice from the last opening, and so 
dividing the channel into two, or by putting in air-tubes, so 
that the air can go in one way and out the other. 

54. Does the law require that the air-roads of a coal mine 
shall be of any specified size ? 

Ans. The law of the State of Tennessee, requires that “the 
intake air-way shall not be less than 20 square feet area and the 
return air-way not less than 25 square feetand in Prussia the 
section of the air-ways is dependent upon the quantities of air 


89 


necessary for the ventilation of the whole mine, including dif¬ 
ferent splits, calculated upon a velocity of 18 feet per second for 
the fresh air-current, and of 22 feet per second for the return 
air-current. 

55. How should air-doors be adjusted in an underground 
road ?• 

Ans. According to the Anthracite Mine Law of Pennsyl¬ 
vania, all doors used in assisting or in any way affecting the 
ventilation shall be so hung and adjusted that they will close 
automatically.” The law is very similar, with respect to doors, 
in nearly all the coal mining States of the Union. 

56. How are the barometer and thermometer used with 
respect to ventilation? 

Ans. They are used to show the variation in the tempera¬ 
ture and pressure of the atmosphere. According to General 
rule 38 of the Mine Law of Great Britain, a barometer and 
thermometer shall be placed above ground in a conspicuous 
position near the entrance to the mine. 

57. How much does the atmospheric pressure vary by a 
difference of one inch in the reading of the barometer? 

Ans. When the barometer rises an inch the pressure of the 
atmosphere is increased about 70 lbs. per square foot. 

58. If the reading of the barometer at sea level be 80 inches, 
what will it read at 100, 200, 1,000 and 2,000 feet above sea 


level respectively? 

Ans. Inches. 

At sea level_ 30.00 

At 100 ft. above sea level.........29.89 

At 200 ft. above sea level____29.78 

At 1000 ft. above sea level..... .28.89 

At 2000 ft. above sea level__ 27.78 


59. If the reading of the barometer be 30.5 inches at the top 
of a shaft, what will be the reading at the bottom, the depth 
being 1520 ft. ? 

Ans. By the rule given in Chap. II., under Barometer, we 


find that 


1520x30-5 


26216 


a—=1*7 will have to be added for the increased 


depth, then : 30'5-f-l'7=32*2 inches, the reading at the bottom. 

60. When the mercury barometer stands at 30 inches, how 
will one of glycerine stand? 

Ans. If we reckon the specific gravity of the mercury at 
13*6 and the glycerine at 1*27, then the relative heights will be 
found thus: 


30x13-6 

1-27 


=321 


61. If the thermometer reads 180 (legs. Fahr,, what will it 
read on the Centigrade scale. 

Ans. 8 2 2~ deg* . 

fa. 










90 


62. If the thermometer reads 45 degs. Centigrade, what is 
that on the Fahrenheit scale? 

Ans. 113. 

63. Have any experiments been made showing the readings 
of the barometer contemporaneously with the issue of gas in 
mines. 

Ans. Yes, in 1881, Mr. J. W. Corbett made extensive obser¬ 
vations at Seaham Colliery on the subject and read a paper 
upon it before the North of England Institute of Engineers, on 
the 3d of July, 1883. 

64. What knowledge do we gain from Mr. Corbett’s obser¬ 
vations ? 

Ans. In his concluding remarks he says : “One lesson sug¬ 
gested by the foregoing water-gauge, barometer and gas 
checking readings is, that as an instrument for the use of all 
connected with colliery operations, the water-gauge may be 
found to be preferable to the barometer, and that if a water- 
gauge is connected with a sealed-up working, its readings indi¬ 
cate nearly accurately the giving off or otherwise of gas in a 
colliery, which the barometer fails to do.” 

65. State the opinion of some other engineer on the connec¬ 
tion of barometer readings and the escape of gas. 

Ans. At the discussion of Mr. Corbett’s paper referred to 
in the last question, Mr. J. Daglish said he might mention that 
many years ago he made a series of experiments at Hetton 
Collieries, with the view of ascertaining and recording the 
pressure of gas and the variations of the barometer, and the 
results he arrived at were precisely such as were given by Mr. 
Corbett, namely, that there was no connection whatever be¬ 
tween the variations in the barometer and the prevalence of 
gas in the galleries of the mine, and that as Mr. Corbett had 
shown them, the gas appeared so long before the barometer 
indicated any change that practically it was of no value ; indeed 
the gas had both come and disappeared before any variation in 
the atmosphere was recorded by the barometer. 

66. Can the heights of mountains be ascertained by observ¬ 
ing the boiling point of water? 

Ans. Yes, the general rule is to reckon a fall of one degree 
on the Fahrenheit scale of the thermometer for every 530 feet 
of ascent. The following table gives examples of the compara¬ 
tive heights of certain places, readings of barometers and boil¬ 
ing points: 



Height above 
level of Sea. 

Ft. 

Barometer, 

mean 

height. 

Boiling point 
of water. 
Fahr. degs. 

Quito___ 

9541 

20-75 

194-2 

Mexico... 

7471 

22-52 

198-1 

St. Gothard__ _ 

6808 

23-07 

199-2 

Garonne (Pyrenees)_ 

4738 

24-96 

203-0 

Geneva _ 

1221 

28-54 

209-5 

Paris__ 

213 

29-69 

211-5 

Sea Level _ _ 

0 

30-00 

212-0 


67. Then, if the heights of mountains can be found by not¬ 
ing the point of ebullition, cannot the depths of mines also be 
ascertained in the same way ? 

Ans. The boiling point of water and other liquids depends 
on the pressure under which they are evaporated ; as we ascend 
a mountain less heat is required, and as we go down a mine 
greater heat is required before ebullition commences, but as a 
variation in the barometer of 1 inch only represents a difference 
of half a pound pressure per square inch, no accuracy in the 
measurement of the depths of mines could be attained by this 
plan. Supposing the barometer to rise 1 inch for each 150 
fathoms of descent, then at 3600 feet this would represent an 
increase in the pressure of about 2 lbs. per square inch. The 
table annexed shows the boiling points of water at the pressures 
given: 


Temperature 

Fahrenheit 

degs. 

Pressure per 
Square inch, 
lbs. 

Temperature 

Fahrenheit 

degs. 

Pressure per 
Square inch, 
lbs. 

32 

•089 

158- 

4-51 

50 

•178 

176- 

6-86 

68 

•337 

194- 

10-16 

86 

•609 

212- 

14-70 

104 

1-06 

230- 

20-80 

122 

1-78 

240-8 

25-37 

140 

2-88 

248- 

29-88 


68. What is the weight of air in a room 30 ft. long, 22 ft. 
wide, and 15 ft. high, with temperature at 62 degs. ? 

Ans. The weight of a cubic foot of air at 62 degs., according 
to Table VIII., Chap. V., is -0763122 lb. ; then 30 X 22 X.b r > X 
•0763122 — 755-49 lbs., the weight of the air. 





























92 


09. What will be the weight of the oxygen contained in the 
room mentioned in the previous example? 

Ans. As air contains 23 per cent, by weight of oxygen, and 
as the room referred to contained 755*49 lbs. of air, the weight 
of the oxygen will be found by saying as 100 is to 755*49 so will 
23 be to 173*76; thus— 


755*49 X 23 
100 


= 173*76 lbs. 


70. Westminster Hall is 290 ft. long, 68 ft. wide, and 110 ft. 
high ; what is the weight of the air in it, the temperature being 
62 degs. ? 

Ans. The weight of a cubic foot of air, according to Table 
VIII., Chap. V., is *0763122. Then 

*0763122 X 68 XJ290JX HO 
2,240 


= 73*9 tons. 


71. How many cubic feet of air at a temperature of 50 
degrees will weigh 1 lb. ? 

Ans. By the table, the weight of a cubic foot of air at this 
temperature is *0788863. Dividing* these figures into one will 
give the answer : 


1 

*0788863 


12*67 cubic feet. 


72. What is the weight of a column of air resting on a table 
6 feet by 3 feet 6 inches ? 

Ans. Nearly twenty tons, but this weight does not press 
upon the table, because it is met by a corresponding pressure 
upwards from the air below the table, due to the weight of all 
the surrounding air. 

73. What is the cause of gob-fires and how are they to be 
prevented ? 

Ans. Gob fires are occasioned through leaving small coal in 
the gobs or goaves ; the action of the oxygen upon the finely- 
divided coal causes it to heat and eventually fire. The best way 
to prevent them is to have all the coal or slack removed, or to 
have the gob filled up. The plan of putting down bore-holes 
from the surface and filling up the gob with the culm from the 
dump has been successfully performed at two or three collieries 
in the anthracite regions of Pennsylvania. The object of this 
was to prevent subsidences, but it would be effective in pre¬ 
venting the accumulation of gas in the gobs as well. 

74. Is coal dust explosive ? 

Ans. Experience in coal mining both in the Old World and 
the New leaves now no longer any doubt that the dust of some 
coals will explode, and that a serious explosion of dust may oc¬ 
cur from a blown-out shot or gunned blast. So far as we know, 
however, whether an explosion will occur or not by a blown- 
out shot much depends upon the chemical composition of the 
coal and other circumstances. Mr. G. M. Williams, the inspec- 




93 


toi* of mines for the Fourth Anthracite district of Pennsylvania, 
says : “We have not yet found that the dust of anthracite coal 
promotes explosions, but it may assist to intensify the heat of 
the gases in an explosion ; and* if it does, the expansion is en¬ 
hanced and a greater force is developed increasing its destruct¬ 
ive power.’’ 

75. It has been stated that flour dust will explode; do you 
believe this to be the case, and can you give the chemical com¬ 
position of flour? 

Ans. Many instances are on record of flour dust exploding 
from a naked light. The following is an analysis of wheat: 


Carbon. 461 

Oxygen.. 434 

Hydrogen. 58 

Nitrogen. 23 

In organ ic matter. 24 


1,000 

76. How does carbureted hydrogen issue from a coal mine? 

Ans. In many cases gradually from the coal beds, in some 

cases it accumulates by degrees in the gobs or goaves, in other 
cases it comes off suddenly in large volumes under great pres¬ 
sure from the coal itself or associated strata. 

77. Does any other gas issue suddenly from the rocks into 
mines besides fire-damp ? 

Ans. Yes, carbonic acid has frequently come off in blowers 
from the working face at the Rochebelle collieries in France, 
with a crackling noise like that produced bj r the issue of fire¬ 
damp. On one occasion three men were killed there and two 
others had a narrow escape. The volume of gas was sufficient 
to foul 176,583 cubic feet of air in a few minutes, and issued 
with such force that 74J4 tons of coal were blown down. It 
took 4)3 days to clear the pit from gas. 

78. Under what conditions will carbureted hydrogen ex¬ 
plode ? 

Ans. When mixed with atmospheric air so that the fire¬ 
damp forms one-eightli to one-ninth part of the whole, it is 
then in the highest degree explosive. 

79. How is the presence of carbonic acid gas detected ? 

Ans. A lighted candle is perhaps the easiest detector of this 

gas, as when it exists in the air to the extent of 10 per cent, the 
light will be extinguished. Anyone going into this gas would 
soon be suffocated. 

80. How is the presence of sulphureted hydrogen gas ascer¬ 
tained ? 

Ans. The presence of this gas is readily detected by the 
peculiar smell it has of rotten eggs. 

81. How much oxygen does a man consume in twenty-four 
hours? 

Ans. Nearly 27 cubic feet. 








94 


82. Wluit gas is found immediately after an explosion of 
fire-damp ? 

Ans. After-damp; this gas consists of 8 parts of nitrogen, 2 
of a gaseous vapor, and one of carbonic acid. In some cases 
when the nitrogen is in large proportion the lamp will burn, 
although the men or horses will be killed in breathing it. 

83. What is binoxide of nitrogen ? State some of its prop¬ 
erties. 

Ans. Binoxide of nitrogen (N 0 2 ) is a colorless gas ; it has 
the remarkable property of instantly absorbing oxygen from 
tlie air, and becoming thereby converted into a brownish red 
vapor of nitrous acid (N O s ), which possesses a highly suffocat¬ 
ing odor. 

84. Give some particulars of sulphurous acid gas. 

Ans. This is one of the products of blasting; a light will not 
burn in it, and miners are occasionally destroyed by it when it 
mixes with carbonic oxide and other vapors caused by the spon¬ 
taneous combustion of coal in gobs or goaves. 

85. What is meant by laughing gas? State some of its 
properties. 

Ans. This is protoxide of nitrogen, which is a colorless, 
odorless gas, having a somewhat sweetish taste. It is a power¬ 
ful supporter of combustion, and a piece of ignited charcoal 
will burn in it almost as brilliantly as in oxygen. When res¬ 
pired it produces a sort of intoxication of a most exhilarating 
character; hence it has commonly received the name of laugh¬ 
ing gas. 

86 . Explain what is meant by Ignis fatuus ; stat<j where 
it is to be seen, and explain the cause of the display of the 
phenomenon. 

Ans. Ignis fatuus means “ a silly light.” It is a meteor or 
light which appears in the night in meadows or marshy 
grounds, and is known by the name of “Will o’ the Wisp,” or 
“Jack o’ the Lantern.” It is occasioned by an ascent from the 
earth of phosphoreted hydrogen gas, derived from animal and 
vegetable remains, and has the peculiarity of igniting itself in 
the air. 

87. Is there any relation between coal and wood in chemical 
composition? 

Ans. There is a relation, indeed a similarity, but as coal 
becomes mineralized it loses the lighter gases and retains a 
larger proportion of carbon ; so that at each stage of mineral¬ 
ization coal has more and more carbon until we come to an¬ 
thracite, which we find contains over 90 per cent., whereas 
wood only contains about 50 per cent. 

88 . What is ammonia, and where is it most frequently met 
with ? 

Ans. It is a volatile compound of nitrogen and hydrogen 
found in all liquids obtained in the dry distillation of nitrogen¬ 
ous bodies. It is to be found in abundance in some under¬ 
ground stables. Ammonia is set free in grinding guano. 


80. It is said that in the neighborhood of Findlay four bore¬ 
holes yielded about 20 million cubic feet of natural gas daily. 
Supposing this had to be substituted by manufactured coal gas, 
how many tons of coal would be required per annum for the 
purpose, and how many acres of a seam 5 feet thick would 
have to be mined to supply it? 

Ans. Reckon one ton of coal to yield 11,400 cubic feet of 
gas, and one acre of coal 1 ft. thick to*contain 1,500 tons. 

20,000,000 X 365 = 7,300,000,000 cubic feet of g-as issuing from 
bore-holes annually. 


7,300,000,000 

11,400 


= 640,350 


tons of coal required to manufacture the gas, 
640,350 _ 

5 X 1500 - y ° ¥ ’ 


the area in acres of a seam of coal 5 ft. thick required to sup¬ 
ply it. 

90. At a colliery in Pennsylvania the volume of air passing 
is 74,580 cubic feet per minute with T 4 7 of an inch of water- 
gauge. What is the power of the ventilation ? 

ANS. 7J -->8° X '4 X 5-8 
33,000 


91. At a colliery in the bituminous regions of Pennsylvania, 
the volume of air in the intake was 54,000 cubic feet per minute, 
but the quantity in the workings was only 29,400. How is the 
difference to be accounted for? 

Ans. No doubt some of the quantity would escape to the 
return at the stoppings erected in the break-throughs, some 
probably would be allowed to pass through the gob, etc. 

92. At one of the mines in the Second Bituminous district of 
Pennsylvania the upcast is 7 feet diameter; what is the velocity 
of the air in feet per second, when the quantity is 35,680 cubic 
feet per minute? 

Ans. Area of shaft = 7 X 7 X *7854 = 38 484, then 
35,680 , , 

3§^843r60 = 1 °‘ 4,,feetpeiSeCOnd - 


93. At one of the collieries in Pennsylvania, the air-shaft is 
9 feet diameter; what is the velocity of the air in feet per 
second with a quantity of 23,843 cubic feet per minute passing. 

Ans. Area of shaft = 63-617 square feet. Then 

23,843 , . , 

- —, „ — = 64 feet per second. 

63-617 X 60 T 1 

94 At a certain colliery, the shaft is 6 feet diameter, and the 
quantity of air passing 17,600 cubic feet per minute; what is 
the velocity of the air in feet per second ? 







96 


Ans. Area of shaft = 28*274 feet, then 

17,600 _ 10*24 feet, per second. 

28*274 X60 

95. Two air-ways of the same length are 8 feet and 4 feet 
diameter respectively, what is the comparative pressure and 
power required to pass the same quantity of air through each? 

Ans. The pressure or power required to pass the same 
quantity of air through round airways of the same length is in 
inverse ratio to the 5tli power of their diameters : 

5th power of 3 = 243. 

5th power of 4 = 1024. 

then the pressure or power will be in accordance with these 
numbers or, 

—— = 4.214 = as 1 is to 4*214. 

243 

96. If the barometer stands at 28*4 inches, find the pressure 
on a square inch ? 

Ans. The height of barometer in inches x .4908, the weight of 
a cubic inch of mercury, will give the result, thus : 28*4 x *4908 
= 13*93 lbs. 

97. When the mercurial barometer stands at 29*75 inches, 
what is the height of the barometer formed of a liquid whose 
specific gravity is 5*5? 

Ans. The specific gravity of mercury being 13.568 then 

29*75 x 13*568 „ Q . . r 

-— = 73*4 inches. 

5*5 

98. If the elastic force of a mass of gas whose volume is 
1000 cubic feet be 30*275 inches of mercury, find its elastic force 
if it be allowed to expand to a volume of 3870 cubic feet. 

Ans. 7*823 inches. 

99. In an air-way 7 feet by 5 feet, passing 12,000 cubic feet 
per minute, what is the velocity of the air-current per second ? 

Ans. 5*71. 

100. How long will it take a current of air measuring 18,000 
cubic feet per minute to pass through an air-course 1*4 miles 
long, 7J4 feet high, and 8 feet wide? 

Ans. The area of air-course will be 8 x 734 — 60. The 

velocity of current will be *8,000 _ ^qq ^ . m j nu t e or 

60 1 

300 -_ ~ ^ per second. The length of air-course is 1760 x 
60 

7990 

134 x 3 = 7920 ft. The time in passing will be _— = 1584 

5 

seconds or 26 minutes 24 seconds. 

60 



97 


101. If the barometer reads 30 inches at the surface, what 
will it show at a depth of 2,000 feet below the surface? 

Ans. By the rules given under the heading Barometer in 


Chap. II., I = P therefore 
20,216 


u x ou 
26,216 


= 2-21 and 30 -f 


2*21 = 32-21, tlie reading of barometer at the depth of 2000 
feet. 

102. If the modulus of the machinery producing the ventila¬ 
tion be -62, what horse-power must it perform in maintaining 
a volume of 120,000 cubic feet of air per minute with a water- 
gauge of 1 -39 inches ? 


Ans 120,000 x 1-39 x 5-2 _ 49 39 pr P 
33,000 x -62 

103. The quantity of air required to ventilate a mine is 
120,000 cubic feet per minute; if the upcast shaft be round, 
what should be its diameter so that the velocity of the current 
will be 500 feet per minute ? 

Ans. The area of shaft should be^^’^^L — 2j$u square feet 

a 500 

and the diameter would bey/ ^/o = 10-96. 


104. If the water-g-auge of a ventilating fan be one inch 
when running at 50 revolutions per minute, what will the 
water-gauge be when the fan is running 90 revolutions ? 

Ans. As 50 8 : 1 :: 90 2 = 3.24 inches. 

105. In the event of an explosion of fire-damp in a coal 
mine, what course should be pursued in entering the mine to 
rescue the employes ? 

Ans. As the result of an explosion is generally to blow 
down stoppings, doors and air-bridges, thereby deranging the 
ventilation, and producing* an unbreathable atmosphere called 
after-damp, the first thing to consider is the restoration of the 
ventilation. The effects are very various, depending on the 
force of the explosion, and the extent and condition of the 
mine. The mode of proceeding* will depend very much on 
these circumstances, but in any case the exploring or rescue 
party should be careful, to take fresh air in along with them as 
they proceed into the mine, which they should do by the down¬ 
cast, and for lights, safety-lamps should be used. Circular iron 
tubes made from thin sheet, 9 inches to 18 inches in diameter, and 
6 feet to 12 feet long, may be readily used for this purpose, or 
canvas tubes made of the same material as brattice cloth, kept 
dilated by internal iron hoops, placed at regular intervals,may be 
used. A waterfall made to operate constantly from the top of 
the shaft down the downcast, may prove of advantage if the 
means of producing* an air current have failed. Presuming 
that the stoppings in the “ break-throughs” are blown down, 






98 


these should he rebuilt as the rescue party proceeds along- the 
intake, and one end of the tubes referred to should be passed 
through into the return, and the other end carried into the 
mine until the next break-through is reached. The air will go 
in by the intake road and go back through the tubes to the 
return air-way ; the next stopping when it is reached, should be 
rebuilt and the tubes connected through this with the return 
air-way again, and carried forward to the next, and so on. 
Doors likewise should be replaced where necessary, and the 
air-bridges restored, but as to what is exactly required to be 
done will depend upon the exigencies of each particular case, 
and the means at hand for aiding in the rescue. Care, prompti¬ 
tude and forethought are all important. A rescuer may go 
forward some little distance in advance of the air by putting 
Glauber salts in a small muslin bag, and placing this over 
the mouth; in breathing, the deleterious gases are by this 
means to some extent absorbed. He should take care, 
however, not to go too far in advance of the air or he will 
probably fall down in the after-damp, the breathing of which 
benumbs the faculties, disturbs the mind, and casts a deadly 
lethargy over the whole body. A breathing apparatus called a 
respirator , constructed to assist in the exploration of mines 
after explosions, may be used. There are various kinds of 
respirators, of which one or two of a very efficient character 
were exhibited to the audience at a lecture, delivered by Sir 
Frederick Abel, on “ Accidents in Mines,” in 1887, before the 
Institute of Civil Engineers, London. One from Prussia was 
notable, devised by Mr. Loch, to enable an explorer to go a 
short distance into a mine and remain there ; the respirator 
being connected by means of a pipe with the external air. 

106. If 10,000 cubic feet of air pass a circular channel of 12 
feet diameter, how much will pass in one having a diameter of 
6 feet ? 

Ans. The quantities will be in inverse ratio to the cube roots 
of the fifth powers of their diameters, or 


V 12 ® 

— = 3 1748 so that the quantity in this case will be 
6 5 


,000 _ 81 
•1748 


107. If the efficiency of a ventilating fan be 60 per cent, and 
the indicated horse-power of the engine working it 40 ; how 
much air will be circulating with the water-gauge at 1*6 inches? 


Ans. 


•60 X 40 X 33,000 
1-6 X 5-2 


= 95,192. 


108. What is the weight of 2,000 cubic feet of air at 50° F. 
under a pressure of 29*5 inches of mercury ? 

1-3253 X 29-5 X 2,000_ 


Ans. W = 


459 -f 50 


.= 153*62 lbs. 





99 


109. If the water-gauge be 1^ inches, what is the ventilation 
pressure in feet of air column (M) with mercury at 30 inches 
and temperature at 62° F. ? 

Ans. As water is 817*1 times heavier than air at this tempera¬ 
ture (See Table XXV., Chap. V.) and as the water-gauge is ex¬ 
pressed in inches, and the motive column in feet, we get 

817 ' 1 = 68-1 as the factor, then M = 68-1 X 1*5 = 102-15 feet. 

12 ’ 

110. There are 10,000 cubic feet of air passing per minute 
along an air-way having a rubbing surface of 24,000 feet, and 
area 20 feet, what will be the water-gauge, the co-efficient being 
•01 lb. per square foot for a velocity of 1,000 feet a minute? 

Ans. = 500 = $ a thousand = .5, then 


•01 X 24,000 X ’5 X ‘5 
20 


= 3 lbs. per square foot pressure, therefore, 


the water-gauge will be A!_ = *57 inch. 
& G 5*2 


111. If the indicated liorse-power of an engine operating a 
fan be 40, and the horse-power of the air be 28, what is the 
percentage of useful effect? 


Ans. 


100 X28 
40 


= 70 per cent. 


112. If a fan at 40 revolutions per minute produce 80,000 
cubic feet of air with a water-gauge of 2 inches, what is the 
horse-power of the ventilation; and if the quantity of air be 
increased to 100 , 000 , what will then be the horse-power in the 
air, the water-gauge, and the revolutions of the fan? 


80,000x2x5-2 

Ans.-331)00 ^=25*21 H. P. The revolutions will be in 

accordance with quantity, therefore, 50. The pressure and 
consequently the water-gauge is according to the velocity 
squared. Then 

as 8 3 : 2 :: 10 2 =3‘12 inches, the water-gauge with the in- 
100, 000x3-12x5-2 ^ A1 , 

creased quantity, and- 3 3 000 -=49-16, the horse-power 

with the increased quantity. 

113. If the return air-course becomes contracted in area, 
what effect has it upon the water-gauge and the quantity of air, 
the ventilating power remaining the same? 

Ans. The water-gauge will rise and the quantity of air will 
decrease. 

114. What method would you adopt for obtaining a large 
amount of air with but a small water-gauge? 







100 


Ans. I would have the shafts and air-ways of a large size, 
by which the velocity of the current would be reduced. 

115. What is the greatest range that has been noted in the 
temperature of the atmosphere? 

Ans. About 130° above and 40 below zero are the extremes 
in the United States East of the Mississippi; and 65° below in 
the Northwest at surface level. It is stated that —81° has been 
observed in northeast Siberia and -|-101 o in the shade in Paris, 
and -(-153° in the sun at Greenwich Observatory, both in July, 
1881. It has frequently exceeded -(-100° in the shade at Phila¬ 
delphia during recent years, all Fahrenheit scale. 

116. What is the range of temperature in a coal mine? 

Ans. About 130° is about the greatest range that can 

occur under normal conditions. The average temperature of a 
coal mine depends on the depth the galleries lie below the sur¬ 
face. The temperature in the workings or galleries of a col¬ 
liery is pretty constant all the year round. The coldest part 
of a mine is at the bottom of the downcast in winter, when on 
some occasions it is probably as low as —30° ; the highest tem¬ 
perature the writer has experienced in the interior of a coal 
mine is about 100°. In case of a gob-fire the temperature would 
be likely to rise to 200° or 300°. 

117. Is there any rule by which the temperature may be 
calculated from the depth ? 

Ans. By experiments it has been found at different places 
that the temperature increases with the depth, but the rate of 
increase is not always the same at different places. From 
observations made in a bore-hole in Germany put down to a 
depth of 5,628 feet, it was found that the regular rate of increase 
in temperature was 1° F. for each 67*2 feet in depth : from the 
readings made at this very deep hole the following formula 
has been deduced for calculating the temperature at different 
depths. 


F=50*68- 


D—19*68 


67*2 


in which D=depth in feet. 

118. At what temperature in air can a human being exist? 

Ans. In answering this we will use the Fahrenheit scale. 
According to A. de Parville, a French authority, a man can 
endure a range of temperature of 252°, that is from—94° to 158°. 
The attendants in the Paris Hammam Baths remain 10 hours a 
day in rooms which are heated up to 158°, 176°, or even 194°; 
Parville on one occasion remained 15 minutes in a sweating 
room, in which the dry air had been heated by his orders up to 
251 *6° from which he went direct into a basin of water at 53*6°, 
so that in less than a minute his body experienced a difference 
of temperature of 198°. Tillaux and Duhamel bore the heat of 
an oven at 263*8° for three minutes. Prince Henry of Orleans 
in his travels over the mountains of Central Asia experienced a 



101 


temperature of —40°. Captain Burck found in Fort Reliance 
the temperature to be —70°, and Captain Douran found —89*7° 
in Fort Ran in April; Lieutenant Peary and his wife in winter¬ 
ing in McCormick Bay, in 1889 to 1890, noted a temperature of 
—96°, and their health was not seriously affected by experienc¬ 
ing a temperature varying from —22° to —58° for three months. 

119. What is the range of atmospheric pressure within 
which a human being can live ? 

Ans. A man can breathe and exist best at the normal atmos¬ 
pheric pressure of 30 inches of mercury, equal to 14*72 lbs.' per 
square inch. He can barely exist at a heighth of seven miles 
where the pressure is only one-fourth of that at the surface. 
A man can breathe and work for some hours under a pressure 
of 234 atmospheres or 3734 lbs. per square inch, as in a diving 
bell, but under a greater pressure paralysis may be produced ; 
some work, however, was done at St. Louis Bridge by men 
under a pressure of 63*7 lbs per square inch. 

119. Do changes of the temperature affect the ventilation of 
a mine? If so, how? 

Ans. Yes. When the temperature of the outer air, which 
enters the mine by the downcast, becomes lower than that of 
the mine, being heavier, it increases the ventilating pressure, 
and consequently improves the ventilation. An increase in the 
temperature of the outer atmosphere has the contrary effect. 

120. How can the number of doors be reduced in a coal mine ? 

Ans. By dividing* the air-current and having a separate split 

or division of air for each district, and building air-crossings or 
air-bridges. 

121. If an airway measuring 7 ft. X 7 ft. has a quantity of 
30,000 cubic feet of air passing per minute, what should be the 
dimensions of a square road to pass 55,000 cubic feet per minute 
with the same pressure? 

Ans. As in square roads the quantities are according to the 
square roots of the fifth powers of the lengths of the sides, with 
the same pressure, the length of the sides will be according to 
the square of the fifth root of the quantities, therefore in this 
case we may say : 

As (\/ s5 ) ! = 7 : s ' 91 - 

|4/ :!(, = 1 *974 and = 2-238. J 

or, as the quimti£ies. are in the proportion of 6 to 11, we may say: 
(^/6) 2 s7::(^/n) 2 :8 .91. 

1-431 and ^/ n = 1*615. J 


As 


102 


or, as the quantities are likewise in proportion to 60 and 110, 
then we may say again : 

As (V^ 0 ) 2 : 7 :: (4/ 115 ) 2 : 8 ' 91 ‘ 

[z^/80 = 2-268 and y/ 110 = 2'56. J 

and as a proof, the pressure for the air-way 7 ft. square, and 
that 8*91 ft. square will be found to be the same by the rule : 

k 8 v 2 
a 


122. What is meant by the motive column , and how is it 
calculated ? 

Ans. It means the pressure in operation to produce the 
ventilation, expressed in feet of air-column or head of air ; or a 
column of air of such a height as to equal in weight the dif¬ 
ference between the weight of the air in the downcast and 
upcast. It is calculated by the following formula : 


M = D X 


T —t 
459 + t 


M — motive column, D = depth of upcast in feet, t = tem¬ 
perature of downcast, T = temperature of upcast, the result 
of which gives the feet of air-column at the temperature of the 
air in the upcast. 

^ T —t 
D X 459-f- T 


will give the length of the motive column in feet of air at the 
temperature of that in the downcast, but it is usual to find the 
motive column for the air in the upcast. 

The motive column may likewise be found by taking the 
"Weight of a cubic foot of air at the temperature of the down¬ 
cast and upcast, and from these figures finding the difference 
of the weight of the air in the two shafts. 

. 123. What is the motive column under the following con¬ 
ditions : Temperature of downcast 50° F., upcast 130° F., and 
depth of shaft 300 feet? 


Ans. 300 X ™ , Z = 47*15 feet, or 
459 -f- 50 

weight of one cubic foot of air at 50° = -0781113 
“ “ “ “ “ 130° = -0675020 

then 300 X -0781113 = 23*43339 

300 X *0675020 = 20*25060 

Difference = 3*18279 


3-18279 

-•067502 = 47 ' 10 asabove ' 


If 100 cubic inches of air weigh 31 grains troy under a 


124. 







108 


barometric pressure of 30 inches, what will the same quantity 
of air weigh at a higher altitude where the barometer stands at 
26 inches, the temperature being the same? 

Ans. The volume of air varies inversely as the pressure, the 
temperature remaining constant, therefore, the diminished 
pressure is to the original pressure as the original volume is to 
the increased volume, or as 26 : 30:: 100 : x. 

The increased volume of air at the higher altitude where the 
barometer is 26 inches, though the temperature is the same, 

30 X 100 ,, „ , , . . , 

is = x = ——-— ----- 115*4 cubic inches. 

vO 

At this altitude, therefore, it takes 115*4 cubic inches of air to 
weigh 31 grains troy ; hence 100 cubic inches would weigh 

X 31 = 26*86 grains. 
llo*4 ° 

125. What units of work are necessary to overcome the 
friction of an air-way 6 feet square, 1,000 feet long, when the 
quantity passing is 10,800 cubic feet per minute? 

Ans. U = - ~ — X q = 6,480. 


126. If, with a pressure represented by one inch of water- 
gauge, 30,000 cubic feet of air pass, what height will the 
water-gauge be when the quantity passing is 50,000? 

Ans. As 3 2 : 1 :: 5 3 = 2*77 inches. 

127. If 5 H. P. circulate 30,000 cubic feet of air, how many 
H. P. will be required to circulate 50,000? 

Ans. As 3 s : 5 :: 5 3 : 23*14. 

128. Here are 100,000 cubic feet of air passing through two 
separate air-courses, one having five times the resistance of the 
other, how much will pass through each? 

Ans. The quantity of air is according to the reciprocal of the 
square root of the length. In this question one may take the 
resistance as the length, 


then the relative quantities will be as 



or as 4472: 1, then the quantities will be 69,098 and 30,902 re¬ 
spectively. 

129. If the average percentage of oxygen in the air is taken 
at .20.7 volumes, what will be the explosive maximum of C H 4 
if two volumes of C H 4 require for their complete combustion 
4 volumes of oxygen ? 

Ans. Two volumes of C H 4 require 4 volumes of oxygen, 
therefore 1 volume of C H 4 will require 2 volumes of oxygen, 
and 20*7 volumes of oxygen will require 10*35 of C H 4 or fire¬ 
damp. This mixed with the air containing 20*7 of oxygen and 
79*3 of nitrogen will make up altogether 110*35 parts. Then as 
110.35 : 10*35 :: 100 : 9*38, so that the maximum explosibility of 




104 


fire-damp is when it is contained in the air to the extent of 9'38 
per cent. 

130. A ventilating fan working at 30 revolutions per minute 
gives a water-gauge of eight-tenths of an inch, what will be 
the speed of the fan when the water-gauge reads two inches ? 

Ans. The quantity of air passing, and consequently the 
speed or number of revolutions of the fan, varies as the square 
root of the water-gauge, therefore, 



X 30 = 47’4 revolutions. 


131. If 9 cubic feet of gas be exploded, how many cubic feet 
of flame will it make ? 

Ans. It is calculated that one cubic foot of gas expands to- 
21-3 cubic feet of flame, therefore 9 X 21*3 = 191 7 cubic feet. 

132. What kind of stoppings are required by law ? How would 
you construct them under various conditions? 

Ans. By rule 2 of the Bituminous Mine Law, Pennsylvania, 
1893, the mine foreman shall cause all stoppings along the air¬ 
ways to be properly built. If for a temporary purpose I would 
erect them with deal boards, say an inch thick; but when required 
permanently I would fill up the “break-through” with loose 
stone or rock for some yards, and at each end would build up a 
wall with brick and cement. By the Anthracite Mine Law all 
crosscuts shall be substantially closed with brick or other 
suitable building material laid in mortar or cement whenever 
practicable, but in no case shall the air stoppings be con¬ 
structed of plank except for temporary purposes. 

133. What precautions would you take to tap water from 
abandoned workings, to conform to law, and to secure the 
greatest safety to the men employed in the mine; and from 
what source could a mine foreman obtain useful data to give 
him an idea of the extent of the danger to be encountered? 

Ans. I should proceed in the manner laid down in Sections 
3 and 4, Article IX, of the Bituminous Mine Law, 1893, and not 
work within 50 feet of any abandoned mine containing a dan¬ 
gerous accumulation of water or gas. Remove the danger by 
driving a drift protected by bore-holes. A mine foreman would 
get useful data by consulting the map of the mine which is be¬ 
ing approached. 

134. What are the lawful duties of a mine foreman ? 

Ans. According to the Bituminous Mine Law of Pennsyl¬ 
vania; he shall see that the regulations prescribed for each 
class of workmen under his charge are carried out in the strict¬ 
est manner possible, that stoppings are properly built, that in 
road grades there shall be a sufficient width between car and 
rib, that undermining be done before blasting, that in fiery 
mines the ventilating furnace, when put out, be not relightecl 
except in his presence, that in case of accident to the ventilat¬ 
ing fan the men be withdrawn from the mine. The mine fore- 


105 

man shall measure the air current at least once a week at the 
inlet and outlet and at or near the faces. He shall give prompt 
attention to the removal of all dangers reported to him by the 
fire-boss or any other person, and when a fire-boss is not em¬ 
ployed he or his assistant shall visit and examine every work¬ 
ing place at least once every alternate day. 

135. State in detail what are the necessary qualifications to 
make an efficient mine foreman, as required by law. 

Ans. By the Bituminous Mine Law of Pennsylvania, candi¬ 
dates for a mine foreman’s certificate of competency shall be 
at least 23 years of age, and shall have had at least 5 years 
practical experience after 15 years of age; shall be citizens of 
the commonwealth, men of good character, and of known tem¬ 
perate habits, and be able to pass the examination for a cer¬ 
tificate of competency. 

136. A mine has four splits, and the amount of air in each 
split is as follows : 1st split, 6,000 feet, 2nd split, 7,050 feet; 
3d split, 7,800 feet; 4th split, 9,750 feet. State how many per¬ 
sons could be employed in each split under the different law¬ 
ful requirements? And if the air-ways are all 7 ft. by 5 ft., 
what would be the velocity in each air-current? 

Ans. The law requires 100 cubic feet of air per man per 
minute, ordinarly, or 150 feet, where fire-damp lias been de¬ 
tected. ■ Then in the 1st split 60 men and 40 men respectively 
could be employed ; in the 2nd split 70 and 47 respectively ; in 
the 3d split 78 and 52 respectively ; in the 4th split 97 and 65 
respectively. 

The velocity of the air in each split would be 

1st = 171 ft. per minute. 

7X5 1 

2 nd = 201 ft. per minute. 

i X o 

3rd i- = 223 ft. per minute. 

7Xo 1 

4th = 279 ft. per minute. 

7Xo 

137. If the ventilation of a mine was insufficient, and the 
ventilating power was working up to its full capacity, what 
would you do under such conditions to increase the ventila¬ 
tion ? 

Ans. The airways must be increased in area, or the current 
divided into more splits or separate currents. Dividing a cur¬ 
rent of air, passing through one air-way, into different splits, 
has the same effect as increasing the area of the original air¬ 
way. 

138. Explain fully the principle involved in natural and arti¬ 
ficial ventilation. 



106 


Ans. See question 33. 

139. Explain how you would ascertain the entire weight of 
air in a ventilating shaft. 

Ans. Ascertain the average temperature of the air. Then 
the weight of a cubic foot is found by the rule 
_ 1*3253 X B 
“ 459 + t. 

This multiplied by the depth of the air in feet will give the 
weight or pressure of the air in pounds. 

140. What is a water-gauge ? What are its uses in mines? 
How is the constant of 5 2 determined? What useful informa¬ 
tion is given to the mine foreman by the use of this instrument 
in mines ? 

Ans. The water-gauge is a glass tube 8 or 10 inches long' 
bent in the shape of the letter |jj ; when used it is partly filled 
with water. It is used to ascertain the difference of pressure of 
the air in two roads separated by a partition in which the 
gauge is inserted. As one cubic foot of water weighs 62’5 lbs. 
at ordinary temperature, then a square foot of water one inch 
deep weighs 

62 5 

= 5‘2 therefore the difference 

in inches in the height of the water in the two legs, multiplied 
by this constant 5'2, will be the difference in the pressure per 
square foot of the air acting on the water in the two separate 
legs of the gauge. By noting the reading of the water-gauge, 
the mine foreman will know whether any doors have been left 
open to allow the air to take a short cut, or whether any ob¬ 
struction has occurred in the air-course. 

141. If the velocity of an air-current going at the rate of 7 
feet per second had to be increased to 14 feet per second, how 
much would the ventilating power have to be increased to pro¬ 
duce the increased rate ? 

Ans. It would have to be increased eight times. The power 
is according to the cube of the velocity, therefore 

(-^) 3 = 2 s = 8 

142. In what proportion does friction increase and decrease 
relative to the flow of air through the mine passage-ways? 
Illustrate by examples, by what means the density of air is in¬ 
creased and diminished? 

Ans. The friction or resistance is increased with the length 
of the road and according to the square of the velocity. If 
with one inch of water-gauge the velocity is 5 feet per second, 
the water-gauge would be 2 inches with a velocity of 7'07 feet 
per second. The density of the air diminishes in proportion to 
the length of the air-channel. 

143. If the air-ways of a mine were to be increased to double 




107 


their length, other conditions remaining the same, in what pro¬ 
portion would you have to increase the ventilating pressure to 
produce the same volume of air? 

Axs. By increasing the length to double, the resistance is 
doubled. The ventilating pressure would have to be doubled to 
produce the same volume of air. 

144. What mode of ventilation reduces the dangers of an ex¬ 
plosion and reduces the friction ? State the reason it is so. 

Ans. By having separate air-currents for each district, the 
friction is reduced and the result of an explosion is likely to be 
limited to the district in which it takes place. The friction is 
reduced because in splitting, an advantage is gained similar to 
that obtained by increasing the area of the air-course. 

145. Show by a sketch, a system of ventilation, which, in 
your opinion would produce "the best distribution of air in a 
mine, and would obviate the excessive use of doors, in order ta 
secure the best sanitary results and the most economical opera¬ 
tions of the mine. 



Axs. The air may be divided or distributed in the manner 
shown on annexed sketch, Fig. 7, which shows a method of 
mining coal by “board and pillar” practiced in the northern 
coal field of England. This method or a modification of it is 
adopted in flat tying seams at a depth of about 900 feet. The 
boards driven westward are 4 yards wide and the pillars left 
are about 20 yards x 24 yards. The arrows show the direction 
of the air currents, and the haulage roads are all in the in¬ 
take. It is intended that the workings on the east side be laid 
out in a similar way to these on the west, so that the different 
air currents would be nearly equally divided. By this plan 
each district would get fresh air and the doors required would 
be reduced to the least possible number. 

140. What are the inexplosive gases found in mines? How 






























































108 


are they produced? Where are they found ? What effects are 
they likely to have upon the workmen ? How are they de¬ 
tected? What are their specific gravities and composition? 
And what would be your remedies to render them harmless? 

Ans. 1. Carbon dioxide. This is known by the name of car¬ 
bonic acid, stythe, blackdamp and chokedamp. It is composed 
of one atom of carbon combined with two atoms of oxygen, 
and has a specific gravity of 1-525. It is produced naturally in 
mines by the breathing of animals, the combustion of lights, 
and by the firing* of explosives, and is commonly given off in 
many mines. It acts upon the human system by making breath¬ 
ing difficult, and induces a sleepy feeling-; men have frequently 
fallen down in it and slept to death. A candle will not burn in 
it, and it is detected from this. 

2. Carbon monoxide, known as carbonic oxide, and white 
damp. It consists of one atom of carbon chemically combined 
with one atom of oxygen, specific gravity *975. It u produced 
when incomplete combustion takes place, and is found where 
gob fires occur. It is known by its sweet odor and deadly re¬ 
sults. It makes the legs tremble of those who breathe it, affects 
the head and causes insensibility; as little as two per cent, will 
cause death. A light will burn well in it, but the flame will 
not become elongated until it forms 12% per cent, of the aerial 
surroundings. With a certain mixture of atmospheric air it 
will explode. 

3. Srdphureted hydrogen. This is composed of two atoms of 
hydrogen chemicalty combined with one atom of sulphur, and 
has a specific gravity of 1*19. It is detected by the strong- 
offensive smell it has. With a certain mixture of atmospheric 
aii* it will explode. 

I*. After-damp. This is a mixture in a mine resulting from 
an explosion of fire-damp. It consists of carbon dioxide, car¬ 
bon monoxide, nitrogen and steam in varying proportions. 

The proper remedy to render these different gaseous mixtures 
harmless is a copious supply of fresh atmospheric air. 

147. What qualifications should a man possess, so as to make 
a good, reliable “ fire-boss ” ? 

Ans. By the Bituminous Mine Act of Pennsylvania, a fire boss 
shall be at least 23 years of age, and have had at least 5 years’ 
practical experience after 15 years of age as a miner ; have 
a good moral character, and be of known temperate habits, 
and by examination demonstrate his fitness to perform the 
duties of fire-boss. 

He should have a practical knowledge of the gases met with 
in mines, and know how to conduct a suitable current of air 
through the various ramifications of a mine. 

148. What is the first duty of a “ fire-boss” when he enters 
the mine? 

Ans. By rule 9 of the Bituminous Mine Law of Pennsylvania, 
he shall enter the mine before the men have entered it and 


109 


before proceeding* to examine it, he shall see that the air cur¬ 
rent is traveling in its proper course ? 

149. What are the lawful duties of afire-boss? 

Ans. By rules 10 and 11 of the Bituminous Mine Law, he shall 
not allow any person except those duly authorized to enter or 
remain in any part of the mine through which a dangerous 
accumulation of gas is being passed in the ventilating current 
from any other part of the mine. He shall frequently examine 
the edges and accessible parts of new falls and old gobs and air- 
courses, and he shall report at once any violation of this act to 
the mine foreman. 

150. Describe the structure of the safety-lamp, and show on 
what principle its safet 3 ^ depends. 

Ans. Davy, in experiments he made before constructing his- 
lamp, concluded that when a flame of an oil lamp was sur¬ 
rounded by a cylinder of gauze having 784 meshes to the square- 
inch, the heat given off by the flame was distributed so rapidly 
by its contact with the fine iron wire gauze, which is a good 
conductor of heat, that the temperature of the cylindrical 
gauze remained too low to ignite an explosive mixture outside 
the gauze. This principle, to some extent at least, applies to 
all safety-lamps, although now in most lamps, in order to have 
a better light, a glass tube or cylinder surrounds the flame, the- 
gauze being placed only at the upper part of the lamp. 

151. Describe the instruments that are most useful in aiding 
the “fire-boss” in determining the conditions of the mine. 

Ans. The water-gauge, which will show him, when placed 
in a partition between the intake and return, if there is any 
change in the pressure of the air ; the anemometer which will 
give him the velocity of the air current; and the safety-lamp 
which will enable him to ascertain whether firedamp is present 
or not. 

152. What are the explosive gases found in cpal mines ? De¬ 
scribe their properties, composition, specific gravities, how and 
where are they produced in mines, and under what conditions 
do they become explosive ? 

Ans. 1. Methyl hydride, or light carbureted hydrogen, C H 4 , 
specific gravity .555, composed of 24.6 per cent, by weight of 
hydrogen and 75.4 per cent, of carbon. When 9^ per cent, of 
this gas is contained in the air it is highly explosive (See ques¬ 
tion 129). It exudes naturally from many coal seams and their 
adjacent strata. 

2. Olefiant gas, C s H 4 , has a specific gravity of 9784; a mix¬ 
ture of about 94 percent, of air and 6 per cent, of this gas will 
be explosive. Under certain proportions of admixture with 
air, carbonic oxide and sulphureted hydrogen are also ex¬ 
plosive. 

153. How would you proceed to look for and detect explosive 
gases in mines ? 

Ans. By using a safety lamp and observing the color and 


110 


form of the halo of the flame inside the lamp. With pure fire¬ 
damp the cap or halo is elongated and blue. 

154. How do you ascertain the additional amount of gas 
that is given off in the mines when the barometer falls from 30 
inches to 29 inches ? 

Ans. Fire-damp is elastic, and will expand in bulk as the 
pressure is reduced, so that gas contained in a gob, supposing it 
to measure, say 1,000 cubic 3 T ards, will expand to 


30 X 1000 
29 


= 1,034, 


on the atmospheric pressure being reduced from 30" to 29". 
The amount of gas that would exude from an acre of gob, 3 
feet high, would be 44 cubic feet on a diminution of the atmos¬ 
pheric pressure represented by .001 of an inch on the baromet¬ 
ric scale. 

One would naturally think that the rate of the issue of gas 
from the solid coal would depend on the pressure at which it is 
contained in the coal, but according to the Royal Commission 
on Accidents in Mines, Great Britain, the outflow of gas from 
holes is not proportional to the maximum accumulation of 
pressure. In any case, at whatever pressure the gas is present 
in the solid coal, I am of opinion that by a reduction of the out¬ 
side pressure from 30" to 29", no material difference will take 
place in the issue of gas from the coal face in a mine. Bearing* 
on this subject, the Royal Commission of Great Britain say, 
“The absence of a general connection between collieiy dis¬ 
asters and barometric changes is practically established ” ; and 
again Professor Chatelier says : “The influence of barometric 
variations is always very small.” 

155. In what stage of the mining operations do the most ac¬ 
cidents occur from explosions of fire-damp? Explain fully. 

Ans. According to the Report of the Prussian Fire-Damp 
Commission, out of 1,633 explosions: 

3*8 per cent, occurred in explorations in stone. 

60*4 per cent, occurred in explorations and in winning coal. 

34*1 per cent, occurred in working or mining coal. 

1*7 per cent, occurred at other points in mine. 

From this it is to be concluded that explosions take place in 
the coal mines of Prussia mostly in opening out a mine, but I 
am under the impression that in the “ board and pillar” work¬ 
ing* of Northumberland and Durham, more explosions occur in 
working out the pillars than in exploring* headings. There is 
a general impression amongst some miners that the greatest 
amount of gas issues from coal seams in opening* the mine by 
exploring headings, but on this point Professor Chatelier says : 
“It is impossible to determine at present the period in the 
work when the greatest discharge of gas occurs.” 








































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